# Which brands/models chainsets / chainrings have perfect centering?



## silva (6 Apr 2019)

Since my newest bicycle I'm plagued with serious chain tension variation.
First a Sugino now also a Stronglight.
Other causes have been eliminated, I replaced chainring/chain/rear cog with new, still directly a tension variation of 2 cm up and down, which is said to result from a 0.5 mm offcenter bottom bracket part (crank/spider/chainring).
On a previous fixed gear, with a French brand TA Specialities Alize Piste, I never had that tension variation, yet I came across a forum post where some1 ranks TA as number 1 worst on this centering issue.
Since this variation is a pain when having to retension, and it is also felt while cycling (alot less fluent), I want to get rid of it, and go for brands/models that are better machined than this crap.
So who has a chainset / chainring that is (near) perfectly centered?
It's a question for people without derailer, because a spring compensates for the tension variation.


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## dave r (6 Apr 2019)

silva said:


> Since my newest bicycle I'm plagued with serious chain tension variation.
> First a Sugino now also a Stronglight.
> Other causes have been eliminated, I replaced chainring/chain/rear cog with new, still directly a tension variation of 2 cm up and down, which is said to result from a 0.5 mm offcenter bottom bracket part (crank/spider/chainring).
> On a previous fixed gear, with a French brand TA Specialities Alize Piste, I never had that tension variation, yet I came across a forum post where some1 ranks TA as number 1 worst on this centering issue.
> ...



I've never come across one thats perfect or near perfect. Have you tried centering the chainring on the spider?


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## Yellow Saddle (6 Apr 2019)

silva said:


> Since my newest bicycle I'm plagued with serious chain tension variation.
> First a Sugino now also a Stronglight.
> Other causes have been eliminated, I replaced chainring/chain/rear cog with new, still directly a tension variation of 2 cm up and down, which is said to result from a 0.5 mm offcenter bottom bracket part (crank/spider/chainring).
> On a previous fixed gear, with a French brand TA Specialities Alize Piste, I never had that tension variation, yet I came across a forum post where some1 ranks TA as number 1 worst on this centering issue.
> ...



This sounds interesting but I'm confused. Are you saying that the chainring has a run-out of 2cm? In other words, it isn't concentric?
Then, what do you mean by 0.5mm BB off-centre?


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## Pumpkin the robot (6 Apr 2019)

General tolerance in the machining I do is +/-0.25mm I find it hard to believe that they accept something being half a mm out. Pay peanuts, get monkeys I guess. 
You may find that the chain ring has an error and the chainset has one, causing a compound error. You would be able to rotate the chain ring to eliminate some of that if that is the case .


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## Yellow Saddle (6 Apr 2019)

Pumpkin the robot said:


> General tolerance in the machining I do is +/-0.25mm I find it hard to believe that they accept something being half a mm out. Pay peanuts, get monkeys I guess.
> You may find that the chain ring has an error and the chainset has one, causing a compound error. You would be able to rotate the chain ring to eliminate some of that if that is the case .


I'm not convinced those figures are right. Something else is going on there, but let's wait, maybe Silva will respond. Stronglight and Sugino have been in the business for a long time, I'm sure they can machine a concentric circle.


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## silva (6 Apr 2019)

Yellow Saddle said:


> This sounds interesting but I'm confused. Are you saying that the chainring has a run-out of 2cm? In other words, it isn't concentric?
> Then, what do you mean by 0.5mm BB off-centre?


1) That 2 cm refers to the distance one can push the chain up and down, so related to the chains tension.
A difference/variation of 2 cm thus means that for ex in a tightest spot of 1 cm up and down, is accompanied by a 3 cm up and down at the most slack point.

2) That 0.5 mm offcenter is the result of a given equation:
- assuming a chain spans (hangs over / distance between sprockets) a distance of 40 cm, then a vertical chain movement in the middle is due to 0.5 mm offcenter of a sprocket.
The equation is
dh= L*sin(arccos(1-dL/L))
dh (deltaHeight) is the tolerance in the middle, total tolerance from highest to lowest point.
L is the tensioned length in the case of a tolerance of 0, so from the rear tooth that engages on the chainring till the front tooth of the rear sprocket.
dL (deltaLength) is the difference in tensioned length in other words the degree of excentricity.


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## Yellow Saddle (6 Apr 2019)

silva said:


> 1) That 2 cm refers to the distance one can push the chain up and down, so related to the chains tension.
> A difference/variation of 2 cm thus means that for ex in a tightest spot of 1 cm up and down, is accompanied by a 3 cm up and down at the most slack point.
> 
> 2) That 0.5 mm offcenter is the result of a given equation:
> ...



Aha. Glad you're still here. Lemme just confirm.

1) You say the chain, at a given position on its drive cycle (upper run), for a given pedal tension, can be pushed up or down with a variance of 20mm, depending on pedal position?

2) OK, I get it, the chain moves up and down as you pedal. Number 2 is just a different expression of Number 1.

Is my interpretation correct?


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## Yellow Saddle (6 Apr 2019)

One more thing. What you don't say is how often viz a vie say, crank rotations, this oscillation happens. Can you clarity that please?


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## silva (6 Apr 2019)

Pumpkin the robot said:


> General tolerance in the machining I do is +/-0.25mm I find it hard to believe that they accept something being half a mm out. Pay peanuts, get monkeys I guess.
> You may find that the chain ring has an error and the chainset has one, causing a compound error. You would be able to rotate the chain ring to eliminate some of that if that is the case .



I've had 2 chainrings of different brands (the one of Stronglight itself that came with their crankset and a UK Velosolo one) and with both I had/have that tension variation, both with 144 bcd.
Before, I had a Sugino XD crankset with a 110 bcd, and also that tension variation.
This all on the same bicycle, that tensions the chain along a bottom bracket eccenter.
My last chainring replacement started with all 3 drive components new, eliminating remaining components as cause.
At the time of the Sugino XD, the tension variation started with 2 cm, then gradually grew (due to wear) to 4 cm, likely due to another reason, a gear ratio of 48/16=3, integer, causing same chain links "hunting" same sprocket teeth, exaggerating local wear and thus wear delta.
The last chainring replacement was a move from 48/16 to 47/16, to avoid this wear concentration within the chain.


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## Yellow Saddle (6 Apr 2019)

silva said:


> At the time of the Sugino XD, the tension variation started with 2 cm, then gradually grew (due to wear) to 4 cm, likely due to another reason, a gear ratio of 48/16=3, integer, causing same chain links "hunting" same sprocket teeth, exaggerating local wear and thus wear delta.
> The last chainring replacement was a move from 48/16 to 47/16, to avoid this wear concentration within the chain.


You don't say how that tension (actually tension inferred by a distance) was how do you a) measure the 20mm and b) ensure that you use the same finger pressure each time you measure?

You are absolutely right that even tooth combinations are problematic and that it is always better to have an uneven number of teeth in one of the sprockets.


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## silva (6 Apr 2019)

Yellow Saddle said:


> Aha. Glad you're still here. Lemme just confirm.
> 
> 1) You say the chain, at a given position on its drive cycle (upper run), for a given pedal tension, can be pushed up or down with a variance of 20mm, depending on pedal position?
> 
> ...


Test situation: bicycle upside down on the ground, with me slowly rotating the cranks, one 360 degrees rotation.
With little force I move the other hand holding an allen key that touches the underside of the upper part of the chain, up and down, with the chain following a certain distance up and down. 
At one point the allen key lifts the chain 1 cm up, at another point that is 3 cm, ie a variation of 2 cm.

When I ride the bicycle, I experience it alike the chain "catches up" every rotation. And I feel a oscillating kinda roughness/vibration in the pedal. It's just crap, ruins the ride, and when drivetrain components have had some wear, it just gets worser.


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## silva (6 Apr 2019)

Yellow Saddle said:


> ... b) ensure that you use the same finger pressure each time you measure?...


It's a little to no force, just enough to overcome gravity effect on the chains mass. Hence the allen key held at its end, the opposite effect of a lever.

To add as much info as I can, in the past very occasional, when moving from forward pedaling to pushing back to slow down, it felt like something moved, and before/after the drivetrain behaved (noise, vibration) different.
I think this was due to a chainring moving abit on its position.
Both Sugino and Stronglight chainset spiders had notches on their arms that left the mounted chainring a littlebit space. The Velosolo chainring lastly mounted on the Stronglight spider, fitted with zero space, no tolerance, I had to very gradually tighten the bolts, making sure none stayed behind too far from the others.
This likely means that the Velosolo chainring is totally unable to move on its position (except on the bolts themselves, but that isn't excentricity).
And this would leave the Stronglight chainsets spider, or taper, as cause for the excentricity.

So this story isn't that obvious, there have been multiple causes for excentricity, and wear concentration (ex the new bicycle had a 5 mm offcenter chainline while the dealer had told me a 100% straight line).

And this last touches another so far untold part: my rear cog is mounted on a brake disc mount (IS disc) and I corrected that 5 mm offcenter chainline with 2 x 2 mm 6 bolt flange spacers. But the spacers are flat, and the IS disc mounts protruding center ring doesn't center the rear cog anymore.
But the rear cog rotates due to the gear ratio 3 times for every chainring rotation, so if it gave any excentricity I would see 3 tension variations for every crank rotation, and there is just 1 variation.
Just to be as complete as possible.


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## Yellow Saddle (6 Apr 2019)

silva said:


> Test situation: bicycle upside down on the ground, with me slowly rotating the cranks, one 360 degrees rotation.
> With little force I move the other hand holding an allen key that touches the underside of the upper part of the chain, up and down, with the chain following a certain distance up and down.
> At one point the allen key lifts the chain 1 cm up, at another point that is 3 cm, ie a variation of 2 cm.
> 
> When I ride the bicycle, I experience it alike the chain "catches up" every rotation. And I feel a oscillating kinda roughness/vibration in the pedal. It's just crap, ruins the ride, and when drivetrain components have had some wear, it just gets worser.



Still a bit confused, but I'm getting my head together. When the bike is upside down, what part of the chain are you tension-testing. The tension run or the return run. And, confirm or not if the high point is just once per crank rotation.

Edit: Forget whether the bike is upside down or not, that confuses the issue. Are you testing the tension run or return run?


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## Yellow Saddle (6 Apr 2019)

silva said:


> When I ride the bicycle, I experience it alike the chain "catches up" every rotation.


That does sound like some sort of eccentricity. May I suggest you remove the chainring/sprocket and draw its outline on paper as well as the bolt holes. Then rotate until you see the place where it seems eccentric and draw that outline. It will show clearly in the drawing if you manage to keep the pencil vertical all the way round. I use that method to check symmetry of templates all the time. 



silva said:


> And I feel a oscillating kinda roughness/vibration in the pedal. It's just crap, ruins the ride, and when drivetrain components have had some wear, it just gets worser.


This is a very typical way that a worn chain on a good set of sprockets presents. If the chain is worn and used on a derailer bike, the derailer spring allows the chain to ride up the sprocket tooth and skate over the top. On a single-speed it doesn't have that escape route and the incoming tooth (front or back) forcibly collides with the chain roller that's in the wrong place for perfect engagement due to chain elongation. That feels like a strong vibration through the pedals.


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## silva (6 Apr 2019)

Yellow Saddle said:


> Still a bit confused, but I'm getting my head together. When the bike is upside down, what part of the chain are you tension-testing. The tension run or the return run. And, confirm or not if the high point is just once per crank rotation.
> 
> Edit: Forget whether the bike is upside down or not, that confuses the issue. Are you testing the tension run or return run?


The upper part of the chain when bike upside down is the return run, but why would that matter, I'm slowly moving the cranks by hand, nearly no force. When I do the test on the "tension" run, it gives just the same result.
And yes, the high (and low) tension point is just once per crank rotation.


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## silva (6 Apr 2019)

Yellow Saddle said:


> That does sound like some sort of eccentricity. May I suggest you remove the chainring/sprocket and draw its outline on paper as well as the bolt holes. Then rotate until you see the place where it seems eccentric and draw that outline. It will show clearly in the drawing if you manage to keep the pencil vertical all the way round. I use that method to check symmetry of templates all the time.


According to the formula, 0.5 mm offcenter suffices, I don't think I can draw that accurate.



Yellow Saddle said:


> This is a very typical way that a worn chain on a good set of sprockets presents. If the chain is worn and used on a derailer bike, the derailer spring allows the chain to ride up the sprocket tooth and skate over the top. On a single-speed it doesn't have that escape route and the incoming tooth (front or back) forcibly collides with the chain roller that's in the wrong place for perfect engagement due to chain elongation. That feels like a strong vibration through the pedals.


But the chain was new/unused, just made on right length. I placed the bike upside down, took off chain, cog and chainring, put new ones, tensioned the chain with the bottom bracket excenter, and noticed the variation.


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## Yellow Saddle (6 Apr 2019)

silva said:


> The upper part of the chain when bike upside down is the return run, but why would that matter, I'm slowly moving the cranks by hand, nearly no force. When I do the test on the "tension" run, it gives just the same result.
> And yes, the high (and low) tension point is just once per crank rotation.


It matters because the return run is subject to up-down movements related to pedal speed and road roughness. It isn't a good place to measure tension by distance inference. The return run could quickly become the tension run if you pedal the other way and I didn't want to go through a rigmarole of questions to figure out whether you were measuring a return run or tension run. 

Are you in a position to trace the chainring? Failing that, if you have a vernier, could you take some strategic measurements?

There is another reason a chain "vibrates" but I won't deal with that now. The fact that you're running a 16 in the rear just about eliminates it.


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## silva (6 Apr 2019)

I have a venier, and just took some measurements, it's a 5 bolts mounted chainring, I measured the 3 distances between non adjacing holes, with venier inwards measuring tips on the hole side closest to the one of the other hole, in other words the mininum distance that can be measured. ande these were all 12.7 mm, with the lower tenths of mm scale of the venier precise matching scale lines so 12.70 cm.
This likely implies that the chainrings center / rotation point lies in the middle of the bolt holes, as they should be.

EDIT 12.70 cm instead of 12.70 mm ofcourse


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## rogerzilla (6 Apr 2019)

Sugino Zen chainrings and EAI sprockets are very round. The best Sugino track cranks (75 or better) should also have concentric drillings. The XD cranks (110 BCD) can be awful; the last pair of RD cranks (130 BCD) I used were pretty good.


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## silva (6 Apr 2019)

I have had a very good experience with a Velosolo rear cog, a 16t, it held out almost 30000 km, with most of that running on a 5 mm offcenter chainline and a 3-4 cm chain tension variation. It outlasted 2 chainrings and 2 chains.
Somewhere at 20000 km I flipped it due to hook fin shape as to start wear the other side of the teeth.
The cog has very thick teeth.
The Velosolo chainring recently mounted shares this characteristic.
The teeth are wide but short.
On a previous fixed gear, I had a TA Specialites 52t chainring, also happy about it, the teeth were different, not as wide but longer.
Question is what wears out first, a thick but short tooth, or a narrow but long tooth?
If I take a guess, I'd say thick but short last longest.
The idea behind this claim is that a thick tooth has a greater contact surface, force is spreaded over that bigger surface, so less pressure per surface unit, and wear is a function of pressure. Abit like a parallel system. A narrow long tooth can then be seen as a serial system, where one after another have to withstand all and fail to do so. 
The Stronglight chainrings teeth also were quite narrow. The Velosolo chainring appears thus promising, time will tell.
My whole drive train looks impressive now, looks like a lasting one, being the goal, only that tension variation indicates the presence of a crap bicycle part, whatever it will be.


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## Pumpkin the robot (7 Apr 2019)

The 12.7cm (5 inches) figure only tells you the holes are evenly spaced on the pcd, not that they are concentric to the axle. You need to measure the holes to the centre of the crank.


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## silva (7 Apr 2019)

Pumpkin the robot said:


> General tolerance in the machining I do is +/-0.25mm I find it hard to believe that they accept something being half a mm out. Pay peanuts, get monkeys I guess.
> You may find that the chain ring has an error and the chainset has one, causing a compound error. You would be able to rotate the chain ring to eliminate some of that if that is the case .


As already mentioned, the recently placed chainring has zero clearance between its inner edge and all 5 crank spider notches, I only got it in its (sidewards) location by tensioning the bolts, unlike the Stronglight chainring that it was replacing.
So I think rotating the chainrings position wouldn't alter any of the current excentricity.
Unless there is some other excentricity cause that I'm still not aware of, it looks like the Stronglight crankset is its cause. The as far as I know other causes have been eliminated.
The previous setups were certainly compound errors, a part due to wear, a part due to chainring, a part due to crankset, aggravated by a 5 mm wrong chainline.

It's almost unbelievable how the producer and dealer of this bike have screwed me. The whole motivation of the purchase was to have a bicycle that finally solved the problems I was plagued with for many years.

The bike is a travelbike ment for internal gears (hub), choice chain or tooth belt, modified to a fixed gear.
I had demanded drivetrain components that were very robust and lasting, wear minimalized. 
I received plain crap. Despite I had hinted the dealer on a motorcycle chain, I ultimately had to find the chain I wanted myself, and that on a wellknown singlespeed shop in the same country as the producer of the travelbike. So they didn't do much search effort.

I had asked a 1/8" drivetrain, the new bike was delivered with a 3/32" Surly stainless steel chainring. I wasn't told and didn't notice, only to discover it when the Surly chainring wore out in a single month.
The dealer then was unable to find a 1/8" chainring with a 110 bcd (for the Sugino crankset).
Meaning the crankset had to be replaced too in order to have the 1/8" drivetrain I had demanded and had been promised.

And then, during the cranksets mount, the spider of this Stronglight crankset turnt out to be narrower, making the chainring void the bike frames chainstay, causing another extra replacement - a longer axle.

Nearly a year later, with the Gusset "tank" chain hanging 45° tilted on two places, and with the dealer telling me he was unable to explain why, I asked the question on a forum, and was immediately told that this was very likely due to a seriously wrong chainline. I was teached how to measure it, did so, and I measured 5 mm off.

When the bike was in production, the dealers last message before delivery was that the bicycles delivery would be delayed some weeks because the chainline wasn't "100% straight" but that they found a solution.
They didn't, they (a Netherlands based dealer named "Santos") decided a deliver as is / bike sold / get paid.
When I confronted the dealer with the wrong chainline forum post, he said that "he had followed my measurements and that they were correct". Pretending alike he didn't knew from the beginning lol.

However, I was able to correct most of the problems myself, a rather shame for the 4300 euro that the bike costed, only this chain tension variation remains of the endless series problems I had, with the possible exception of a rear wheel running 5 mm aside the front wheel, because when I measured the chainline I discovered that the center of the spoke flanges was that much out of the center of the wheel mount pads, so the wheel should be spoked abit alike an umbrella to compensate for this, and I still didn't check this. I did notice that my rear tire wears out quite more at 1 side than in the middle.

This to tell the whole story, which may answer some questions before asking.

And as it looks like now, I'll have yet another further cost, a second replacement of the chainset to one that IS machined precise enough to not have a chain tension variation. Being the goal of my topics question. I found out it's smarter to ask other cyclists/mechanics than to dealers/producers whoms highest priority is a sale.


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## Yellow Saddle (7 Apr 2019)

silva said:


> I have a venier, and just took some measurements, it's a 5 bolts mounted chainring, I measured the 3 distances between non adjacing holes, with venier inwards measuring tips on the hole side closest to the one of the other hole, in other words the mininum distance that can be measured. ande these were all 12.7 mm, with the lower tenths of mm scale of the venier precise matching scale lines so 12.70 cm.
> This likely implies that the chainrings center / rotation point lies in the middle of the bolt holes, as they should be.
> 
> EDIT 12.70 cm instead of 12.70 mm ofcourse



This measurement doesn't take into account the outside perimeter of the chainring. You have only eliminated the fact that the ring does not precess (providing the crank is perfect).

I think you'l get a better picture if you measure from bolt hole to tooth root, if you can figure out a way to make the measurement perfectly so that you measure the same feature each time.


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## Pumpkin the robot (7 Apr 2019)

Measuring the pcd of the bolts to the root of the teeth will only work if the amount of teeth is a multiple of the amount of the bolts (5 iirc) otherwise you will need to do a bit of trig.


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## Yellow Saddle (7 Apr 2019)

Pumpkin the robot said:


> Measuring the pcd of the bolts to the root of the teeth will only work if the amount of teeth is a multiple of the amount of the bolts (5 iirc) otherwise you will need to do a bit of trig.


Yup, nothing wrong with some trig on a Sunday morning.
Who doesn't love it before breakfast?
I suggested to the OP that we need a trace-out of the ring in multiple positions. That is simple and it never lies. I do this with templates I design for an obscure hobby of mine and the brutal truth of flip-flopping a template to see if it is symmetrical often stuns me and chases me to the fridge for a beer and a deep breath.


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## silva (7 Apr 2019)

I'll try that paper outline on a spare same of the mounted chainring, so that I don't have to break apart the bicycle once again lol.

edit, nah, it's impossible to judge, if I have to keep the pencil straight up, then the thickness of its tip causes it to draw several mm's away from what I'm trying to outline, and the chainring thickness is about the same as the height of the protruding pen of the pencil, causing it to not reach the paper half the time.
So what about pencil not straight up, but tilted so as to draw as close as possible to the chainrings edge?

edit2, just did the latter, drawed the inner circle, the bolt holes and the teeth outline, but now I'm not sure what to do next. If I rotate for ex 1 bolt hole, the teeth outline ceases to match, in this case there isn't even any other match than the original hole, making it unusable to compare. If I rotate around the inner circle, all bolt holes match in every position. But that doesn't exclude excentricity - the whole of inner circle and both holes could bave another center than the center that the teeth have.

By the way, the producer of the chainring states CNC machined, shouldn't that exclude any center deviation?

edit3, I think I found a method, I put a ruler so that the clockwise directioned edges of 2 bolt holes are on it, draw a line, and repeat this 6 times. I end up with lines that form a jewish david star.
Then, from the outer intersections of those lines, I repeated it to form another, smaller david star. After a second repeat same way, I ended up with a so small david star that I can visually estimate its center accurately, where I draw a dot.
Then, I did a multitude measurements of distances from the dot towards the inner circle, and found these all equal. This probably proves that the bolt holes have the same center as the inner circle.
And last, I did a multitude measurements of tooth tips towards the center dot, and these all measured 98 mm.
So if aboves method would suffice, this would prove the chainring as not the cause of my chains tension variation.


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## Yellow Saddle (7 Apr 2019)

silva said:


> I'll try that paper outline on a spare same of the mounted chainring, so that I don't have to break apart the bicycle once again lol.
> 
> edit, nah, it's impossible to judge, if I have to keep the pencil straight up, then the thickness of its tip causes it to draw several mm's away from what I'm trying to outline, and the chainring thickness is about the same as the height of the protruding pen of the pencil, causing it to not reach the paper half the time.
> So what about pencil not straight up, but tilted so as to draw as close as possible to the chainrings edge?
> ...



Excellent. I would have been very surprised if that had been the case. Now for the crank. see if you can somehow create a centre point in the bolt that holds the crank on the BB. Perhaps, remove the bolt but don't pull the crank. Now use a standard common compass to draw a circle bisecting the chainring bolt holes. See if the crank is concentric around its centre point.

I'll also suspect the freehub - what brand/type is that and the sprocket. Off you go, you have plenty of homework to do.


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## Pumpkin the robot (7 Apr 2019)

CNC machining is not foolproof. Drilling a hole, I would expect a deviation of about 0.1mm unless the hole is machined by a smaller cutter, rather than drilled.
As the chainring would be machined in one operation, I would expect it to be pretty concentric.
I think the issue you have would be the centre of the chainset not being concentric to the bolts that secure the chainring.


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## silva (7 Apr 2019)

Yellow Saddle said:


> Excellent. I would have been very surprised if that had been the case. Now for the crank. see if you can somehow create a centre point in the bolt that holds the crank on the BB. Perhaps, remove the bolt but don't pull the crank. Now use a standard common compass to draw a circle bisecting the chainring bolt holes. See if the crank is concentric around its centre point.
> 
> I'll also suspect the freehub - what brand/type is that and the sprocket. Off you go, you have plenty of homework to do.


Heh, I'm a bicycle tech rookie, the very reason I went to fixed gear was to simplify the common / high frequent maintenance and replacement jobs so far that I would be able to do these themselves, so I wouldn't depend anymore on dealers that in the end took 6 upto 9 months for a revision, causing my spare bike drivetrain to be worn before the other got repaired.
So I will certainly not try to remove a crank bolt, if I screw something up I can't even get at a repair place with it, requiring a pickup by the repairer and a delivery later on.
But I'll try to figure out a centre point in that bolt. I don't have a compass but I think that between the old tools my dad had there are some metal compass alike tools that can be fixed under a certain angle, so if I fold it open so that it ranges the distance crank and chainring bolt centers, then fix the angle, I can check the other chainring bolt distances. 
But I have doubt about the accuracy. 0.5 mm equals 2 cm vertical tension variation, and I can't see how I can visually be that accurate.

There is no freehub / freewheel, it's a fixed gear.
The sprocket is a Velosolo bolt on cog 16t see http://www.velosolo.co.uk/shopdisc.html
It's mounted on a "Surly Ultra single speed disc silver 13x10mm 36G"
And as already said here somewhere, between the cog and the disc mount, there are 2 x 2 mm spacers to correct the chainline, purchased and mounted myself. As also said, this is a potential cause for excentricity of the cog, because the spacers (see CNC 6 Bolt Cog Spacer on same page) are flat thus do not "pass" the centering ring through to the cog. 
(I also found out that there are hubs with IS disc mount that don't even have such a centering ring).

But if that was the reason for the excentricity then I would see 3 peaks and valleys in the chains tension, and that is not the case. Also, the degree of excentricity would be 1/3 of the chainrings.
So I would say that the rear of the bicycles drivetrain can be eliminated as cause.

Since the chainring has been eliminated today as cause (IF I can assume that the mounted one is perfectly the same as the spare one that was delivered the same time), all that remains is the Stronglight chainsets spider/whatever closer to the axle, meaning that if I want to get it solved, I'll have to spend bucks once again.

And that was the reason for my topic here, to avoid a third not well machined component purchase, by asking others if they know brands/models that proved themselves as machined with a smaller tolerance than that 0.5 mm.


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## silva (7 Apr 2019)

Btw, Yellow Saddle, since my search for a longer lasting bicycle chain I developed an interest in roller chains generally, this appears as being a specific field of interest of you, and therefore you may be able to give some definite answers on some questions I found different answers for.

1)
My last bicycle, where all above is about, also suffered an annoyant initial (new chain) of the bottom bracket eccentric chain tensioner: nearly at the end of its range, inflicting me the job to remove a couple chain links during the life span of the chain, quite shortly after placement new chain.
My move from an 48t to a 47t chainring had, aside being a solution for the integer gear ratio caused wear concentration within the chain, a second reason: it allowed the chain to be 2 links shorter, and brought that initial eccenter position close to the begin of its range.
Now, there was an alternative solution, the insertion of a type chain link that is known as "halflink". And chains exist that are fully built with such halflinks. Of course, the halflink has to be available for the chain, but supposing it is, I have read on several industry oriented websites that halflinks (also named "offset links") would form weak points in the chain.
For ex https://www.diamondchain.com/frequently-asked-questions/


> However, due to the reduction in the chain’s working capacity, offset links, of either type, are not recommended in performance oriented drives.


or https://tsubaki.eu/catalogs/Tsubaki-CATM-EN-2016.pdf


> Although offset links can be used when there is an odd number of links in the roller chain, it is better to use a design that requires an even number of links





> Offset link plates are bent at the center, and the resulting concentration of stress at the bend can cause a fatigue break. Avoid using offset links in high-stress applications.





> An offset link is used when an odd number of chain links is required. The pin and two plates are slip fit. The fatigue strength
> is 35% (applicable to ANSI chain) lower than that of the chain itself.


35% is a serious reduction, but would this matter for a bicycle application in the case if the link plates were 3/16" - double as thick as a common chain? Often I see wide chains advertised as higher strength, but I cannot see how, since a chain is as weak as its weakest part, and if the internal width and thus the rollers/bushings stay same sized, regardless how thick the plates are, the chain won't be "stronger" than before. I see as big benefit the increased contact surface between pens and plates, spreading the force over a bigger area and thus less force per surface unit, and thus less wear. Since an offset link has same room for plates / thickness, they wouldn't void that wear benefit, so that they would give me more gear choice options without shortening need within chains lifespan.
What are your thoughts on this?

2) My current Gusset "tank" chain, see https://www.tartybikes.co.uk/chains/gusset_tank_chain_18_inch/c7p331.html has internal width of 1/8" but the plates of a 3/16" chain (a combination of 2 standards that is typically called "heavy duty version").


> - Fed up of breaking chains? Then you should be looking at this beast!
> - Super Heavy Duty 1/8” chain.
> - Pin Length 11.6mm.
> - Pin riveting power 300Kg (standard chains are around 150kg, KMC Kool chain is 250kg)
> ...


There are contradicting / wrong specifications about amount links but since I purchased a dozen of these, I know for sure: 102.

Recently, I discovered this: https://www.tartybikes.co.uk/chains/kmc_k910_316_inch/c7p12836.html


> Ultra strong chain from KMC!
> - Super wide 3/16" construction with extra thick plates gives this chain a whopping max. load capacity of 1500kg!
> - 13mm pin width. (EDIT: 12.9 mm also listed and probably more correct)
> - The chain tool we recommend for this chain is a Park CT-7, alternatively we are happy to split the chain to your desired length before dispatch - just put a note at checkout. Please remember the split link will add extra length to the chain (1/2" in total) when fitted!
> ...



I wonder what (wear related) benefits the KMC may have relative to the Gusset.
The KMC chain appears to be a full 3/16" chain. Meaning the internal width is 3/16" instead of 1/8".
From experience, I know that 1/8" is hugely beneficial relative to 3/32", very likely due to the mechanical contact surface being 50% bigger.
But so far I was unable to source any 3/16" bicycle sprockets, yet, KMC produces such a chain, alike they are available.

Now, imagine the KMC used on my current sprockets. So a 3/16" internal width chain on a 1/8" chainring. This gives the links some room to move sidewards, or, reduces the sideways contacts between the sprocket teeth and the chains inner plates.
And most of all, the contact surface between pen and bushing, 1 of the 2 causes of elongation under tension and thus wear on the sprocket teeth, increases a further 50% to double the one of a 3/32" chain.

But, do you see drawbacks too?
Weight is for me non important.
And second, do you happen to know any companies producing 3/16" chainrings for bicycles?

Regards and your knowledge in this matter appreciated.


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## Yellow Saddle (8 Apr 2019)

Question 1: Offset links are only a problem with strong machinery, such as conveyor belts and stuff that very powerful, even more powerful than me. So don't worry, I've never seen an offset link crack, ever. An offset chain on a big roller chain such as the ones you cited will be a very bad idea. The thick plate has to make a sharp bend in a very small space. Put cyclical tension on that and it will crack. But that's not a cyclists issue. 

Question 2: I never fiddled with singlespeed and fixies and whatever I sold to people who don't believe that the freewheel and gears were a good invention was all 1/8th stuff. Which means I'm a poor source of advice for such oddities. But, there's no need to go to 3/16th. A quick glance at the KMC EU website seems to not even list 3/16th. Others on here may know better.

Yes, wider chains have a longer wear life but it is not a linear relationship. You don't get double for double, for example. Bushing chains live much longer than bushinless chains though.


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## derrick (8 Apr 2019)

Would it not be easier just to stick a dial gauge on it?


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## rogerzilla (8 Apr 2019)

3/16" is old-school BMX. You can get the stuff but maybe not in useful sizes, and maybe not a fixed cog (only freewheels). Your chain tool may not work with 3/16" chain; you may need to shorten it with a hammer and punch to drive out the rivet.


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## silva (9 Apr 2019)

I have a chain tool code named "YC-324", origin YE CHOU INDUSTRY CO., LTD. Taiwan
It exists since a long time, has been through some remodellings and is part of many toolkits, and is labeled as a workshop chain tool.
It works on the Gusset "Tank" with 3/16" sideplates.
The basis (where the link is supported) is adjustable. So it works on about any 1/2" pitch chain.
It has a spare pin and a position fixer so that once you found out how far you have to turn the pin, you can "remember" it with that limit fixer.
It's the best chain tool I came across so far. And it costs half the price of many so called "pro" tools.
Before I found it, I used hammer and punch. as basis I used a steel block where I drilled a hole in for the pin.


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## silva (14 Apr 2019)

But I'm sure there are some fixed gear riders out there that can mount a new chainring new cog new chain without seeing a chain tension difference the size of an egg. :P
Those must have a better machined crank/spider and must know brand/model.


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## silva (29 Apr 2019)

Today I came across this article: https://www.peterwhitecycles.com/fixed.php
It refers some brands/models with better centering.
Apparently, the term used for this offcenter is "runout".
Listed as perfect/very precise:
Sugino Grand Mighty Gold
Sugino 75
Listed as very small runout:
TA Alize

On my 2 previous fixed gears, I had TA Alize Piste chainrings, it's possible that the crankset is also TA.
Which would explain why I never noticed a chain tension variation. Apparently better machined than the Sugino XD and Stronglight Track 2000.
And those older bicycles costed a quarter and less than this new one. 

-


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## mangid (30 Apr 2019)

silva said:


> Today I came across this article: https://www.peterwhitecycles.com/fixed.php
> It refers some brands/models with better centering.
> Apparently, the term used for this offcenter is "runout".
> Listed as perfect/very precise:
> ...



I run Sugino 75 DD cranks on a Hope BB, with Sugino Zen chain ring (48T), EAI Gold Medal (18T) and Izumi Super Toughness. Just replaced the chain ring (22K miles), sprocket (9K), chain (9K), BB (20K) and it's all running spot on ;-) Crankset has 37K on it in 2 years.


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## silva (1 May 2019)

Heh, checked that all and it makes a hell of a mighty price ticket.

New for me - a stainless steel (probably an expensive grade) sprocket with titaniumnitride coating. 

But I wonder, a sprocket and chain life of 9000 miles, and even that chain ring 22000, that appears not that much to me.
Before the replacement my topic here is about, the replaced Velosolo bolt on cog had been mounted 18 months on a bicycle that I travel 50-60 km daily with, and weights 25 kg without extra luggage (see the pic in my avatar) - that's 27000 km or 18000 miles. And most of it with a 5 mm wrong chainline (and this offcenter caused chain tension variation).
At 17 UK pounds for a cog, that's not bad. And the about same price costing Gusset chain, same circumstances, "stretched" 1/2" in as much as just 2 months less. 
Last, the chainring of the Stronglight Track 2000 chainset (the one causing the chains tension variation), not that happy about it. It lasted 15 months but its teeth were seriously worn when it was replaced, no tooth tops left anymore. Much better than Surly's soft 304 stainless steel chain ring (that I had to replace after just a couple months) but no fair comparison due to being 3/32" instead of 1/8".
The Velosolo ring that I mounted now, has equally wide and tall teeth as their cog, so looks promising.

But the chain part of the drivetrain is the most influential part on wear, if it becomes longer under tension the pitch increases and this eats up the sprocket teeth 
regardless how hard and tall they are.
So the first step to improve a drivetrains wear rate is a harder wearing chain. I experienced 1/8" as a major improvement from 3/32". If 3/16" sprockets existed, I'd certainly go for these, but so far I only found a 3/16" chain from KMC, also a brand that I started to dislike because I their advertising doesn't mention things it should. I'll keep searching though, it also took many months (including those before I ordered the new bike) before I discovered Gussets tank chain.


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## silva (22 Aug 2019)

It's now 4.5 months ago that I replaced the Sugino crankset with the Stronglight 2000.
And changed the chainring from 48T to 47T, as to get rid of the 48/16 ratio which concentrated instead of spreaded out the wear over the chain links.
Since some weeks, I again hear series of ticks while pedaling.
From experience with the Sugino and the 48/16 I know that this is due to uneven wear within the chain. The tension variation didn't grow much further since the replacements, unlike with 48/16 so the slight change from gear 3:1 to 2.9375:1 really seems to have solved that part of the problem.
Still series of ticks, after a chain retensioning less loud, but they become louder again till a next retensioning.
I thought first it was due to the pedaling force that has 2 peaks (just over the top position of every pedal) and thus wear the teeth there more than others.

But I decided a test, like I did during the time of 48/16, "shifting" the chain 12 links in forward direction over the chainring. This caused the ticks to be gone for a month.
If uneven chain wear would not be the cause of these ticks now, the ticking should just remain what it was.
Just back from a test ride - instead of 5-6 ticks at every pedal stroke, I now get just 1.

All this together, forms an elimination to a single cause: excentricity within the chain rings mount / de spider of the crankset.
So it does look like the only final, complete solution to this problem is a perfectly centered chainset / ring mount.
As long as it isn't, I will be plagued by having to shift around the chain on a regular basis.


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## silva (4 Oct 2019)

Couple days ago, I was given a new to me explanation for a chain tension variation: a not centered, or a seriously worn, spindle (bottom bracket).
I don't get that well, the spindle IS the center of the bottom bracket and anything mounted on it. So if a spindle is declared as not centered, where is that center relative to?


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## Ian H (4 Oct 2019)

I'm slightly puzzled by all this. I've ridden fixed (not exclusively) for very many years, and seldom had totally even chain-tension around a pedal stroke. But it has never been something I notice when riding the bike. Just a guess, but I wonder whether the roughness is something to do with an out-of-alignment sprocket and chainring.


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## silva (4 Oct 2019)

The chains of my two previous fixed bikes don't show a tension variation. The real question here is what do you mean with "totally even"? With my last bike, with new chainring, cog and chain, when I tension the chain so that I can push it 1 cm up and down, I can push it 3 cm up and down elsewhere.
It's annoyant to first have to find the tightest location at every tensioning. On top of that annoyancy, a second annoyancy is that when I fasten the screws on the eccentric bottom bracket hole, the chain tensions abit more so I have to try to estimate a certain lower tension in order to get the one I want.
My previous bikes tensioned the chain along moving the rear wheel front/back.
That was much less hassle, only that the nuts over time fret out the frame ends.


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## dave r (4 Oct 2019)

silva said:


> Couple days ago, I was given a new to me explanation for a chain tension variation: a not centered, or a seriously worn, spindle (bottom bracket).
> I don't get that well, the spindle IS the center of the bottom bracket and anything mounted on it. So if a spindle is declared as not centered, where is that center relative to?



I've not come across a not centred spindle, its a new one on me, but I have come across a chainring thats not centred on the spider and rings and cogs that aren't perfectly round.


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## silva (5 Oct 2019)

dave r said:


> I've not come across a not centred spindle, its a new one on me, but I have come across a chainring thats not centred on the spider and rings and cogs that aren't perfectly round.


As said, I didn't even understand, a spindle IS a center how can be out of center. I replied to the dealer for more explanation but no answer yet. 
Months ago I checked (a longwinded method along drawing it over on paper then drawing lines, new lines at intersections and so on) my chainring based on Yellow Saddles comment, and I found it as centered.
Elimination has narrowed the cause down to the bottom bracket, the spindle also sits there, so it could be a cause, only that I don't get precisely what the relative is to judge on or off center, to what, what other center.
Until now I assumed only the spider on the driveside itself, it's mechanical shape, could be a bottom bracket cause.


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## dave r (5 Oct 2019)

silva said:


> As said, I didn't even understand, a spindle IS a center how can be out of center. I replied to the dealer for more explanation but no answer yet.
> Months ago I checked (a longwinded method along drawing it over on paper then drawing lines, new lines at intersections and so on) my chainring based on Yellow Saddles comment, and I found it as centered.
> Elimination has narrowed the cause down to the bottom bracket, the spindle also sits there, so it could be a cause, only that I don't get precisely what the relative is to judge on or off center, to what, what other center.
> Until now I assumed only the spider on the driveside itself, it's mechanical shape, could be a bottom bracket cause.



I assume the spindle he's talking about is the bottom bracket axle, and the only way that can be off centre is if the bottom bracket is very badly worn with movement in the axle.


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## silva (7 Oct 2019)

dave r said:


> I assume the spindle he's talking about is the bottom bracket axle, and the only way that can be off centre is if the bottom bracket is very badly worn with movement in the axle.


Upon asking, another explanation I've been given is that a square axle can be offcenter, causing the center of the spider of the crankset to rotate in a circle.


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## Milkfloat (7 Oct 2019)

I do think you over think things. Just ride it, maintain it and replace stuff that breaks.


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## Grant Fondo (7 Oct 2019)

Milkfloat said:


> I do think you over think things.


Very good, that made me larf.


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## dave r (8 Oct 2019)

Milkfloat said:


> I do think you over think things. Just ride it, maintain it and replace stuff that breaks.




Thats spot on, just ride it.


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## silva (10 Oct 2019)

Milkfloat said:


> I do think you over think things. Just ride it, maintain it and replace stuff that breaks.


It's a fixed gear, I have to retension the chain regularly, a chain tension variation makes that harder, is a wear concentration cause, and is annoyant when pushing back due to the "dead" gap brought by the tension variation.
Is thinking of a solution, then overthinking?


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## dave r (10 Oct 2019)

silva said:


> It's a fixed gear, I have to retension the chain regularly, a chain tension variation makes that harder, is a wear concentration cause, and is annoyant when pushing back due to the "dead" gap brought by the tension variation.
> Is thinking of a solution, then overthinking?



Yes


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## silva (11 Oct 2019)

dave r said:


> Yes


Your refusal to recognize a problem as such is not my problem, chain tension variation is.


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## Milkfloat (11 Oct 2019)

dave r said:


> Yes



I agree. I ride thousands of miles per year fixed on a cheap non-centred chainring with a cheap chain. I replace the chain about every 2k miles, mainly because it is cheap. I don’t rotate the chain, unless it happens to do it on its own when the wheel is out, I rarely bother to region either. I just ride it.


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## silva (11 Oct 2019)

Milkfloat said:


> I agree. I ride thousands of miles per year fixed on a cheap non-centred chainring with a cheap chain. I replace the chain about every 2k miles, mainly because it is cheap. I don’t rotate the chain, unless it happens to do it on its own when the wheel is out, I rarely bother to region either. I just ride it.


Chain: 13.95 €
Front sprocket: 32.95 £
Rear sprocket: 16.95 £
I replace the chain about every 20k miles, mainly (sole reason...) because it's... worn.
I rotate/flip the chain when I notice wear differences between the drivetrain parts.
I find every work on a bike too much work, so I try to decrease it towards zero, and a centered chainring is just another step on that road.
I don't want a bicycle that inflicts me work every evening. Because I just wanna use it to go from A to B.

Same for that stupid hydraulic brake system on my 62 mm tyres bike. If I have to take out / put in a wheel brake modules on both sides need to be unmounted OR I have to deflate>reinflate the tyre. I wasn't warned about it and when I started to suspect it when seeing pics but a "no ofcourse not that would be silly" was the answer. Recently I decided enough crap and went for mechanical brakes like on my previous bike. Then the crap gets reduced to a simple hooking out a V brake.

You say every 2k miles you replace a chain, lol, did you order plastic ones?

If I find a well-centered chainring then wear differences will decrease and then I have to mess 'round with the bike less and have more time and money to do the things I want to do. Ofcourse. Imagine you carry a backpack that every return home requires sewing. What would you do, everytime sewing or a new same one? I'd choose a better quality backpack brand instead lol.


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## Milkfloat (12 Oct 2019)

I bought a pack of 10 chains costs less than £3 each. They are very much disposable items for me. My sprockets are about £5 but so far seem fine.


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## silva (12 Oct 2019)

I find it crap to have to replace a chain every 2000 miles. I'd go for a better quality and if it lasts 3 times the miles at 3 times the price I'd go for it, because that's still a win (no replacement work).


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## rogerzilla (12 Oct 2019)

It's only an issue if the chain, when set to avoid binding at the tighest point, is slack enough to derail elsewhere. I've only ever seen that on kids' bikes with stamped steel chainrings. Buf they're s/s so an unshipped chain is not as dangerous.

NJS keirin kit tends to be very round and expensive. The irony is that most keirin riders, for reasons unknown, run super-slack chains.


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## silva (13 Oct 2019)

rogerzilla said:


> It's only an issue if the chain, when set to avoid binding at the tighest point, is slack enough to derail elsewhere. I've only ever seen that on kids' bikes with stamped steel chainrings. Buf they're s/s so an unshipped chain is not as dangerous.
> 
> NJS keirin kit tends to be very round and expensive. The irony is that most keirin riders, for reasons unknown, run super-slack chains.


Reasons I consider it an issue is that it voids an even wear spread, that pedaling is less smooth/rougher, that when I switch from pushing forward to pushing back there's a dead gap and that when doing a standstill before a red light / whatever waiting cause, it's harder to maintain balance, due to that dead gap.
Keirin looks like the cyclists version of 100 m sprint. Wear/maintenance does not matter, and a very slack chain likely gives some speed benefit.
Fact is that my two other previous singlespeeds>fixed gear bicycles never had a noticeable chain tension variation. Shimano cranksets, couple weeks ago I took a look, the cranksets were Shimano though forgot the model, have to look again for it.
So apparently, precise (centering) manufacturing doesn't require big bucks, the bikes costed 1/3 down to 1/4 of my current problematic bike with its 1001 problems.
But the cranksets are of a different and unusable for the current bike type. Maybe Shimano has some compatible models that maybe are precise centered.
But more recently, according to a lbs dealer, a square taper kan also be a cause. So it's then still not sure that the crankset is the cause.
It's not a hell of a problem, but still inflicts me a recurring hassle, that's why I want to at least try to find a solution.
It's like my current chain with 3/16" plates. It took half a year to finally find it / know its availability. I bought 1, tried 1 and it proved itself. Then I bought a whole stock of it. Because you never know, if that single company ceases then I'm thrown back to the begin. Now I have a buffer. If I find a crankset (or spindle) then that's again such a reference, ofc less important since it's not like a crankset has to be replaced as much as a chain/cog...


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## silva (22 Dec 2019)

Followup, since some weeks I have an octalink bottom bracket and Shimano 105 crankset mounted.

Pity was that I had (according to dealer) to change the chainring due to octalink not available with the current chainsets 144 bcd. So I had to mount a new / unworn chainring so that a 1 on 1 comparison with isn't possible.

The chain tension variation is still present.

I just tensioned the chain once again.
Measured with the bike hanging with its horizontal tube on a stander, measuring the same in both up and down running parts.
The chain tension is:
- maximal (tightest, set to about 1 cm up and downwards moveability), seen from the driveside, when the right (driveside) crank arm is on the 1:30 clock position.
- and minimal at the 7:30 clock position.
I made a dozen chain rotations, and those two clock positions stayed.

I do not have this tension variation on my previous fixie, that I used in a same fashion.
Aside: during the crankset/axle replacement, about a month, I have used that previous fixie.

I've ran out of ideas of the cause of the tension variation.
The variation cyclus is 1 max/min per chain rotation, if pushing the pedals/cranks would be a cause then I'd have 2 maxes every chain rotation.
Chain replacements (so far 2 so 3 in total, 2 brands) didn't affect it
Chainring replacements (so far 3 so 4 in total - 2 due to bcd change, 2 brands) didn't affect it.
Crankset replacements (so far 2 so 3 in total, 3 brands) didn't affect it.
Axle replacement (square taper to octalink) didn't affect it.
What else can be out of center / causing this?
Remember, earlier this year I have replaced chainring, cog and chain in one time - simultaneous, to notice a 2 cm up and down pushing tension difference directly afterwards, without any riding yet.

I now ran out of ideas. Can't even think of any possible other than above listed cause.
How different is my previous fixie to the new? The previous bikes chain was tensioned by moving the rear wheel backwards in its mount. The new one has a bottom bracket eccenter. But that just fixes (along two bolts) the axle into a certain position inside the shell, a position that doesn't change during riding or whatever else rotates the chain.


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## silva (22 Dec 2019)

rogerzilla said:


> It's only an issue if the chain, when set to avoid binding at the tighest point, is slack enough to derail elsewhere. I've only ever seen that on kids' bikes with stamped steel chainrings. Buf they're s/s so an unshipped chain is not as dangerous.
> 
> NJS keirin kit tends to be very round and expensive. The irony is that most keirin riders, for reasons unknown, run super-slack chains.


Keirin riders do not care about wear, all they care is the max speed on the short distance they play their game over.
About the opposite of my case so not really a reference and any irony is thus 'foreign' too.


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## Stompier (22 Dec 2019)

There is probably no such thing as a perfectly round chainring or sprocket - some are more round than others, but you will get tension variations on even the most expensive kit. Maybe if you ran a Sugino Zen chainring and a EAI Gold Medal Pro sprocket you might get closer to 100%, but for that price, who knows.

Just accept the tension variation. As long as the chain is not unshipping - or binding, there is no issue. And if it is dropping, it might be more to do with your chain line than chain tension.

There is a school of thought in track racing (not one I necessarily subscribe to fully) that says that you should run your chain as 'slack' as possible - the definition of 'possible' being if you spin the crank/wheel, hold the bike up horizontal and the chain doesn't fall off, then it's not too loose. Most people seem not to go that far, but it's a useful measure nonetheless. The ideal behind the 'slack' chain is the lower the tension, the lower the friction loss, up to a point.

Also - just a point on NJS. The NJS stamp on some track kit is a mark of 'compliance' - not necessarily a mark of 'quality'. Most of the NJS kit is pretty good anyway, but the NJS stamp doesn't necessarily make it better than something without the stamp.


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## rogerzilla (22 Dec 2019)

If it bothers you, you either have to pay hundreds of pounds for the accurately-made kit, buy another cheap crankset and hope you strike lucky this time (cheaper ones aren't made to be bad but there is a bigger range of accuracy, so some will be spot-on) or - at no cost - centre the chainring on the spider.

I know you say there is no space between the chainring and the spider, but you can create some. Get a file and take half a millimetre off the inner five tangs of the ring. That will give you enough wiggle room to eliminate, or greatly reduce, the tight spot. Fasten the bolts fairly loosely, fit the chain, find the tight spot and then tap the chainring towards the sprocket with a mallet. Keep doing this until you get as little tension variation as possible, then tighten all the bolts firmly using a cross pattern (don't tighten adjacent bolts).


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## silva (22 Dec 2019)

The bike costed over 4000 and you say that I bought cheap cranksets?

Really lol, I've better things to do than filing off cranksets spider places and centre chainrings all the time. Because tell me, if I would succeed in this, at a next ride, a push forward and a push back to slowdown, the thing can move again offcenter, with me having to recenter it again, and again and again.
Fact is that my 2 previous bikes (also singlespeed>fixed gear) both didn't suffer a chain tension variation, and costed a fraction.
Apparently it doesn't need big bucks to get a decently centered crankset. And hence I asked here. Price tag clearly proved as no quality indication.


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## rogerzilla (23 Dec 2019)

Well, the problem won't fix itself, however much you complain about it on the Internet.


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## silva (23 Dec 2019)

See this topic... trying to find a well centered chainset... tried octalink but actually wanted a similar hollowtech 2 setup since that proved itself as well centered on my previous bike. 
That's what I'm after, "complaining" is stating the problem, and I don't want ersatz solutions that inflict me the extra work caused by the chain tension variation just somewhere else, shifting problems is not solving problems.


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## presta (23 Dec 2019)

Here's a few engineering facts of life: no components are made exact because it's not possible to make _anything _exact, so they are made to a tolerance, and components aren't made to a tighter tolerance than necessary because it's expensive. Components made to an unnecessarily tight tolerance won't be competitive against ones that aren't. So that begs the question what tolerance is necessary. 

You've made a case that chainrings for a fixie rather than a derailleur are better with a tighter tolerance, but is anyone actually marketing precision chainrings specifically for fixies? I don't know the market, but I've not noticed any. How many fixie riders would even notice the difference let alone be willing to pay extra for it? You refer to better rings you've had before, but were these made to a tighter tolerance, or were they wide tolerance parts that just happened to be close to their nominal size? If you pick a component from a batch made to a wide tolerance some will inevitably be 'accurate' just by chance alone, but that's a random lucky dip, you can't just go to the LBS and expect to be able to buy another like it.


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## Stompier (23 Dec 2019)

Agree 100%. Tolerance is compensated for on single speed and fixed wheel bikes by running a somewhat less than drum-tight chain.


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## silva (24 Dec 2019)

presta said:


> Here's a few engineering facts of life: no components are made exact because it's not possible to make _anything _exact, so they are made to a tolerance, and components aren't made to a tighter tolerance than necessary because it's expensive. Components made to an unnecessarily tight tolerance won't be competitive against ones that aren't. So that begs the question what tolerance is necessary.
> 
> You've made a case that chainrings for a fixie rather than a derailleur are better with a tighter tolerance, but is anyone actually marketing precision chainrings specifically for fixies? I don't know the market, but I've not noticed any. How many fixie riders would even notice the difference let alone be willing to pay extra for it? You refer to better rings you've had before, but were these made to a tighter tolerance, or were they wide tolerance parts that just happened to be close to their nominal size? If you pick a component from a batch made to a wide tolerance some will inevitably be 'accurate' just by chance alone, but that's a random lucky dip, you can't just go to the LBS and expect to be able to buy another like it.


100% disagree.

Be sure you notice it, pedaling feels like a pulsation, pushing back has a dead range due to the chain having to tension first then a shock, tensioning the chain lasts 10 times longer because you have to find the tightest spot first and keep it there in order to not have have a binding wheel and not end up ruining bearings, and it causes asymmetrical wear on the chains links, aggravating all the problems.

In contrast to what you seem to insinuate here - it's not a pickpecking problem, it's a major one.

I have had two previous bikes without derailer- I'm riding singlespeeds since a decade and fixed gear since 2017, 2 different brand bikes, bought with 1 year inbetween, the last one with the hollowtech 2 bottombracket, the first one with square taper. I didn't suffer that chain tension variation. Maybe ALL batches those days were produced with GOOD tolerance?
And that GOOD tolerance back then didn't quadruple their price.

It's very simple, I was sold crap, there are still producers out there that are more honest, the question of this topic asks for those, and the most reliable answers are from other people that bought from them, not from dealers.


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## silva (24 Dec 2019)

Stompier said:


> Agree 100%. Tolerance is compensated for on single speed and fixed wheel bikes by running a somewhat less than drum-tight chain.


I noticed how you try to minimalize the problem with that "somewhat less".
You also had to ignore with it the basic of the problem: drum tight on one spot couples to a superslack other spot.
According to many sources a chain tension is stated as a 1 cm up and downwards movability, that's what I do and since that is the general consensus it's NOT "drum tight". In the bikes first period, the superslack other spot started with 3 cm up and down, and grew to 5+ cm up and down. Yeah, I DID notice it during riding lol. And it also was dangerous since I tend to push back rather than use the brakes and the dead range (to get the chain tight in that direction - the lower part - the return run), unpredictable on the moment, inflicted me the need to always use the brakes too, "in case".


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## Stompier (24 Dec 2019)

I don’t think anyone can help you, by the sound of it. And you still haven’t said what bike you have that is giving you all these unfathomable problems.


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## silva (24 Dec 2019)

Stompier said:


> I don’t think anyone can help you, by the sound of it. And you still haven’t said what bike you have that is giving you all these unfathomable problems.


That's just pessimism, in the past I found durable components, along positive posts found on forums here and there.
See, that's something I noticed over time: what is advertised most, usually is biggest garbage. The qualitative stuff you have to search and discover.
So your thought is just what it is, your thought. If you tried to help, thanks.
About the bike I talked about.... it's just the one in my avatar... since my presence on this forum. Thanks for your attention.

To illustrate my point of view and my attitude along a today story: my rear mudguard is broken (divided) at a mount place. Why: because the hydraulic brakes are mounted on a fork that cannot be removed without nearly entirely disassembling the bikes rear so dealer probably forced it in its place, causing the plastic to develop cracks (due to the width of the rear mudguard (62 mm tyres)). Adding to the problem is that this brake mount fork (horseshoe shaped) has to sit entirely till the fender to reach its 2 mount points at the brake modules locations.
Due to the break, mud gets sprayed on my chain and rear bags.
So I just removed brakes and wheel and saw a part off from a mtb fender I found along the road (which is btw typical me haha), my soldering iron is now heating up, I will heat up the plastic while bending it so that its cross section follows the required curve to fit in the inside of the broken fender, then I will drill a hole on the place of the frame mount then I will put this fender part in front (inside seen) of the current broken one, and fix it to the frame. And then I will fix both ends of the broken fender on the "new" made-up fender along drilling holes and hooks from washing line bend as needed.
And yet another problem that had to be "complained" about, and addressed / fixed. Only that I didn't need to ask questions to find a solution.
.


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## Stompier (24 Dec 2019)

The pic tells me nothing - other than you seem to cart around a lot of stuff. Just the make and model would be useful?


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## keithmac (24 Dec 2019)

Have you considered Gates Carbon Drive?.

I wouldn't go back to a chain now.


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## silva (24 Dec 2019)

Stompier said:


> The pic tells me nothing - other than you seem to cart around a lot of stuff. Just the make and model would be useful?


I think that will tell you little more, hence I didn't find it useful to mention - it's a local brand specialized in travel bikes: Santos, frame model "travelmaster 3+", a kinda specialized frame designed to serve for several drivetrain and tyre width configurations.
And yes haha I cart arount alot stuff, my biggest load was 70 kg on a 30 km trip. A kinda unique occurrence but it happens regularly that I carry a backpack with 20-30 kg fruit on top of standard load.
Sometimes when I read that people chose aluminium bolts to save a couple grammes I can't avoid shaking my head.
Basically, I only have some bikes, don't want a car anymore, and when you have to live like that and not rely on others, you NEED luggage capability like that.


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## silva (24 Dec 2019)

keithmac said:


> Have you considered Gates Carbon Drive?.
> 
> I wouldn't go back to a chain now.


I have considered that from the beginning, and initially thought to chose it, but upon reading about it (not only the advertising but also user reviews) I came to the conclusion that it wasn't what I want my bike to be - it's too expensive in parts, way less common, too critical in mounting, much easier to damage than a steel roller chain, and DIY harder.
btw the bikes producer and dealer also came to that conclusion, on which reasons I don't know, also I heard on other subjects given reasons that turnt out to not have been the real ones.
But feel free to sum up your positive experiences with belt drives. It's not like that I'm locked up with roller chains, only that at that moment a belt drive appeared as a more con than pro.
What is for sure is that I never want gears back. Way too fast wear and other trouble (alike wet/frozen>sudden freewheeling in both directions and there you are in the middle of nowhere and rain / frost with nothing you can do).
Fixed gear rules my day. I understand things are different for other people, but not in my case / usage.
Likely the real reason for bikes producer/dealer was that if it was already that hard to get a straight chainline on their frame (the best they achieved with roller chain was 5 mm off, the rest I had to find a solution for myself), that for a belt drive this would be even more problematic - and it's more critical than a chain on this.

Edit: addition to that much easier to damage - know what: just parking your bike somewhere between other bikes, with no other choice, is already a recipe for disaster in the belt case, a steel roller chain can take a beating / a sharp object, a belt not. Just look in a city at all the bike wreckage around. I once returned to see my bike displaced with its chain mangled in the bike parking frame so that I had to use force to free it. The chain didn't end its life there, a belt certainly would. Hell, just look at how you have to fold a spare belt in order to not damage it.

This is a large version of my avatar pic.






Now it has more luggage capability, the wire basket on top of the rear rack has now twice the size and I mounted a small backpack (one I found thrown away along the road - a kid one) under the handlebars. I've put my bike tools and spares in because concentrated weight and thus counterbalancing the bike when alot loaded on the back.
I had to move forward my front and move backward my rear light due to the modifications.

My roller chain weights 550 gr - it's a 1/8" model with 3/16" plates so that a little rust or salt isn't fatal.





The pic is taken at the time that the chain hung tilted 45 degrees due to the 5 mm wrong chainline.
That plate below is a mudguard for the chain - mud and snow sticks and travels the entire rear wheel mudguard circumference to deposit itself near the bottom bracket (and chain). That made a hell of a difference.

I made mudguards for my shoes too:






So now you see how desperate I am.


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## Stompier (24 Dec 2019)

So I've just looked it up and the bike appears to have standard 'vertical' dropouts - not track ends - is that correct?


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## silva (24 Dec 2019)

Stompier said:


> So I've just looked it up and the bike appears to have standard 'vertical' dropouts - not track ends - is that correct?


Yes, hence the bottom bracket eccenter I mentioned here and there - that's for tensioning the chain.
The bike has qualitative components, stainless steel bolts, washers, strong materials, but there are some bad choices good mechanics wouldn't make, and dito bad execution. For ex nearly nothing was greased, they used red loctite on the rear disc mount cog bolts that were too short, so that the hubs aluminium thread got damaged and had to be tapped out, and after a month riding my chainring wobbled so that it scratched the frame. Also galvanic corrosion of aluminium due to stainless they didn't take into account.
Last week I moved forward my front light and the lights cable sat in the way of the allen head bolt that fixed the lights support to the bikes crown bolt location. I had to file out the aluminium hole to make room.
Today the bolts of the rear mudguard - same story, stainless so not rusted but no grease at all, and white powder on the thread, frame thread aluminium that got dissolved due to galvanic corrosion. Grease would have prevented that. A luck not severe enough to pose mounting problems.


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## Stompier (24 Dec 2019)

silva said:


> Yes, hence the bottom bracket eccenter I mentioned here and there - that's for tensioning the chain.



That's never going to work as well as track ends - as evidenced by these and other threads of yours. I really do think you're barking up the wrong tree. If you're serious about running fixed/SS, then at least get a frame which does it justice. Or fit a standard BB and use a chain tensioner.


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## newfhouse (24 Dec 2019)

silva said:


> I made mudguards for my shoes too:
> 
> View attachment 497717
> 
> ...


Your shoes need some polish.


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## keithmac (24 Dec 2019)

silva said:


> I have considered that from the beginning, and initially thought to chose it, but upon reading about it (not only the advertising but also user reviews) I came to the conclusion that it wasn't what I want my bike to be - it's too expensive in parts, way less common, too critical in mounting, much easier to damage than a steel roller chain, and DIY harder.
> btw the bikes producer and dealer also came to that conclusion, on which reasons I don't know, also I heard on other subjects given reasons that turnt out to not have been the real ones.
> But feel free to sum up your positive experiences with belt drives. It's not like that I'm locked up with roller chains, only that at that moment a belt drive appeared as a more con than pro.
> What is for sure is that I never want gears back. Way too fast wear and other trouble (alike wet/frozen>sudden freewheeling in both directions and there you are in the middle of nowhere and rain / frost with nothing you can do).
> ...



All good points, I'm 5,000 miles in on mine with no need to adjust the belt (had a play with the Gates app though).

In all my years of working on Motorcycles I've only ever replaced one belt due to stone damage.

It seems you've been ripped off by the bike builders, that is a significant amount of money for a sub standard product.

This is my left hand side adjuster, both are decoupled from the frame and easily replaced if necessary.

You've lost some valuable adjustment at the rear with the eccentric Bottom Bracket, if only for fine tuning the axle position.

Hope you get it sorted, one point Gates setup is they have decades of experience making pulleys/ sprockets and belts so they are very good at manufacturing to close tolerances. My belt is nigh on identical tension anywhere along the crank rotation (within a couple of hz).


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## silva (24 Dec 2019)

newfhouse said:


> Your shoes need some polish.


Does my bike look alike I wear a costume?


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## newfhouse (24 Dec 2019)

silva said:


> Does my bike look alike I wear a costume?


Yes, a bit.




No offence intended.


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## silva (24 Dec 2019)

Stompier said:


> That's never going to work as well as track ends - as evidenced by these and other threads of yours. I really do think you're barking up the wrong tree. If you're serious about running fixed/SS, then at least get a frame which does it justice. Or fit a standard BB and use a chain tensioner.


Feel free to explain why an eccentric at the bottom bracket is never going to work as well as track ends.
It's abit more work that losening, pushing back wheel and fastening a couple nuts (losen two allen bolts, then an allen key to turn the eccenter in its hole, taking into account that the bolts tension the chain abit further then tighten the bolts again).
But acceptable and benefit no brake pads to realign unlike when wheel is moved backwards and also wheel straight. And no fretting of nuts into dropout alu.

This is all not related to centering / chain tension variation no?


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## silva (24 Dec 2019)

newfhouse said:


> Yes, a bit.
> View attachment 497733
> 
> No offence intended.


Do you see polished shoes? I don't.
Maybe your nose blocks your view?
No offence intended.


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## silva (24 Dec 2019)

keithmac said:


> All good points, I'm 5,000 miles in on mine with no need to adjust the belt (had a play with the Gates app though).
> 
> In all my years of working on Motorcycles I've only ever replaced one belt due to stone damage.
> 
> ...


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## Stompier (24 Dec 2019)

silva said:


> Feel free to explain why an eccentric at the bottom bracket is never going to work as well as track ends.



The most compelling explanation is going to be all of your posts in this thread. If an eccentric BB was that good at providing the levels of adjustment needed, there would be no issue and we wouldn't be having this conversation.


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## silva (24 Dec 2019)

keithmac said:


> All good points, I'm 5,000 miles in on mine with no need to adjust the belt (had a play with the Gates app though).
> 
> In all my years of working on Motorcycles I've only ever replaced one belt due to stone damage.
> 
> ...


I've read reports of belts snapping 3 times in a row, I've read about problems with centering (not the centering I talk about in this topic but just to stay in the middle of the sprocket), among other problems. Only the advertisers never have problems.
If belt drives were that superior on short and long term then there would be as many as electrical bikes now. 
Take into account my usage of the bike. It has to survive heavy loads, rough handling, accidental hits and vandalism. A roller chain cannot be cut by a kitchen knife. A belt can. Hell, one can take a cigarette lighter and burn your belt to inoperation.
In the belt case, fine tuning of axle position is not a luxury, it's an essential, with a lose hanging chain you can still ride home, with a lose belt you can walk home.


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## silva (24 Dec 2019)

Stompier said:


> The most compelling explanation is going to be all of your posts in this thread. If an eccentric BB was that good at providing the levels of adjustment needed, there would be no issue and we wouldn't be having this conversation.


It's not about the fineness (= your "levels") but about excentricity / offcenter somewhere.
Weird that after all posts I still have to remind you.


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## Stompier (24 Dec 2019)

silva said:


> It's not about the fineness (= your "levels") but about excentricity / offcenter somewhere.
> Weird that after all posts I still have to remind you.



Well, we're just going round in circles (no pun intended). I'm not going to bother replying anymore, just to say with that frame, you will never achieve what you are looking for. Signing off.


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## keithmac (24 Dec 2019)

silva said:


> I've read reports of belts snapping 3 times in a row, I've read about problems with centering (not the centering I talk about in this topic but just to stay in the middle of the sprocket), among other problems. Only the advertisers never have problems.
> If belt drives were that superior on short and long term then there would be as many as electrical bikes now.
> Take into account my usage of the bike. It has to survive heavy loads, rough handling, accidental hits and vandalism. A roller chain cannot be cut by a kitchen knife. A belt can. Hell, one can take a cigarette lighter and burn your belt to inoperation.
> In the belt case, fine tuning of axle position is not a luxury, it's an essential, with a lose hanging chain you can still ride home, with a lose belt you can walk home.



I genuinely feel quite sorry for you, if you think someone is going to set your drivetrain on fire.

Have you got tamper proof letterboxes and full water supplied fire suppression systems at home just in case someone sets your house on fire?.


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## keithmac (24 Dec 2019)

The CDX and CDN have been "self centering" for at least 5 years, it would be an effort to try and derail the belt.

I'd be genuinely interested to read your findings if you can post some links up?.


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## silva (25 Dec 2019)

keithmac said:


> The CDX and CDN have been "self centering" for at least 5 years, it would be an effort to try and derail the belt.
> 
> I'd be genuinely interested to read your findings if you can post some links up?.
> 
> ...





keithmac said:


> I genuinely feel quite sorry for you, if you think someone is going to set your drivetrain on fire.
> 
> Have you got tamper proof letterboxes and full water supplied fire suppression systems at home just in case someone sets your house on fire?.


I'm not your slave, Google to find the reports, that's what I did when weighting pros against cons.
I didn't say set on fire, I said "and burn your belt to inoperation"
It doesn't even need a cigarette lighter, a lit cigarette already suffices to melt a belt tooth so that it deforms and renders your belt and bike inoperative. That's the drawback of nylon and other such plastics compared to steel.

Both belt and chain have pros and cons.
To state it in your own posting style: "I genuinel feel quite sorry for you, if you think that belts only have pros".
In your post #80 you said:
"You've lost some valuable adjustment at the rear with the eccentric Bottom Bracket, if only for fine tuning the axle position."
Explain me the value of rear side adjustment. I agree that thread of a bolt allows finer tuning than turning an eccenter module in a frame hole, but such fine tuning is not required for a rollerchain, it is for your belt case (one of the critical points I mentioned).
And in this topic it's even laughable that you use it as argument, since a 2 cm tension variation ruins any finetuning result.
Tell me, imagine you suffered some eccentricity in your belt drive sprocket mount (or wherever), what would be the consequence for your belt operation? I can still ride somewhere, likely you have to walk.

About my general attitude towards handling risks, well I do keep some filled 1.5l bottles water nearby typical sources of fire / highly inflammable stuff alike sprays in pressurized containers. The bottles just stand between the latter. I have the place, it costs nothing, and it may make a big difference in any rare occasion something goes wrong.
Does that make me somebody that lives in a nuclear shelter: no.
Notice here how I moved from a silly small thing to a huge big thing?
Well, that's what you just did.

Try to stay ontopic, I want to solve a problem being an excentricity in a drive component - I'm still not sure but elimination brought me to the bottom bracket as place of cause - by replacing the badly centered component with a better centered one.
I have had 3 cranksets on this bike, a Sugino XD, a Stronglight Track 2000 and now a Shimano 105 no idea which model of the series. The initial (chainring, cog, chain totally new) chain tension variation of all was about 2 cm up and down (so ex 1 tightest 3 most slack). The first time it grew to 4 cm (so ex 1 cm - 5 cm) in a single month - 1500 km due to the 48/16 ratio. During the year that I rode like that (including a 5 mm wrong chainline) I repositioned the chain all the time in order to spread the wear more. Since I replaced the 48 to 47 the tension variation just stayed what it was so the most worst part of the problem I already solved. Now I try to find the solution for the remaining part.
My last attempt (the Shimano 105) was to eliminate square taper axle/crank as cause, since I noticed after my left crank breakage that the replacing crank initially sat tilted and during further retensionings of its bolt gradually aligned. So I asked for the same Hollowtech 2 as on my previous bikes but since the chainline made that impossible I had to try the early octalink.
Unless I overlooked a cause all the time - all that remains is now the crankset choice.

This forum section is singlespeed/fixed gear. Some singlespeed and all fixed gear people active here do not have a derailer on their bike and thus nothing that compensates an offcenter drivetrain component. Do 'we" all suffer a chain tension variation as big as 2 cm?


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## keithmac (25 Dec 2019)

I wouldn't know how much eccentricity you could get away with on a belt drive as mines been built properly.

Same with all the Harley's and Buells I've serviced.

20+ years of fitting toothed kevlar belts in various applications has shown to me they are a very robust solution and practically zero maintenance.

You need to invest in some decent measuring equipment, someone mentioned a dial gauge further up the thread. These can measure down to 100ths of a mm and ideal for deciding which part of your drivetrain causing the runout.

Ask a local machine shop to centre your font crank/sprocket assembly in there lathe, they can easily measure down to 100ths of a mm and rule that out one way or the other.

I must have fitted approx 1000 chain and sprocket kits to motorcycles and only had 1 issue with eccentric sprockets, due to customer supplying cheap sh1t, we found 3 makes of well machined sprockets and only use those to avoid such problems.


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## silva (26 Dec 2019)

Why would I buy expensive measuring equipment if elimination already brought me this far?
By now I know the bike in and out, I worked numerous hours on it to make it like I want / need it to be.
Some months ago, when Yellow Saddle said to check the chainring (but doubted it was the cause) I thought some way to check the ring without tools, I drawed its shape over on paper then drawed lines from teeth edges to diametrically opposed teeth edges so that I ended up with david stars that I then did the same on, until the star became so small that I accurately could estimate its center, then I measured back to the teeth, and found the chainring as centered.
According to another, math skilled person, a tension variation of a roller chain, sized as 2 cm vertical, equals a 0.5 mm offcenter. There is 1 tight and 1 slack point per pedal rotation, which again points to the bottom bracket as cause.
As said, centerings of chainring I don't accept as a solution since they are interim - there is nothing that prevents the chainring to move again offcenter, especially in a fixed gear case where one pushes back to slow down.
I.... just.... need... a... sufficient... centered... chainset. Like on my previous fixed gears.
I can't keep on replacing chainsets just to try. The ones I did were forced (bcd change needs, broken cranks).
It's waiting on some other fixed gear rider that doesn't suffer this tension variation and has a crankset that is compatible with my setup, or whoms brand does sell a compatible.
When found and replaced, the bike has finally become what I asked for when I ordered it, two+ years ago.

See, solutions that say buy this buy that, I'm tired of those. That's what I did in the past and they didn't deliver solutions only costs and more problems. And I have to solve it myself, as I found nearly all LBS's as untrustable to do a good job.
After I measured myself the chainline, to find 5 mm off, I wanted a "pro" opinion as confirmation and visited another LBS. He even refused to measure it and told me that one never gets a chainline correct for such a bike. One week later I decided to just trust myself, I ordered spacers, mounted these, and as later on proved: it made the chainline right - it put an end to the 45 degrees tilted chain halve lengths.

About belts, I have nothing to add to what I previously said. ex I didnt want hydraulic brakes but there was no alternative for my case (as turned out - disc brake mount 'hijacked' for rear cog). Just one day after riding the bike home I sat stuck with a front wheel blocked by 1 hydraulic brake pad. The reason was found as the wheel mount quickrelease that apparently hadn't been tightened enough by the dealer (likely because the handle sat on the good point in the way of a luggage front rack) so that a shock shifted it in its mount. Imagine I hit something of something hit me (a wheel) and its moved or deformed. Well the hydraulic brake modules have to be dismounted in order to free it.
Later story: hydraulic line broke near top tube due to poor mounting (to sharp corner). A steel cable doesn't brake easy.
Remember my melting / burning belt to inoperation? Well, one can ruin a bikes hydraulic brake by just cutting the thin pvc plastic of the oil line. Not so with a cable brake.
So no thanks. I have to manage to get home myself.
Which was btw also the reason that I arrived at the idea to put quickrelease brake handles on both sides instead of the one side and the other a hard to reach Torx head bolt. Some exercising and now it's over with the pain to deflate the tyre in order to get the wheel out.
Belt drive is too critical in its requirements for my application. I have no problem with roller chains only with a tension variation and as said: if I'd put belt sprockets and belt on and the cranks are the cause then it doesn't make a difference at all, only that with a chain I get home while a belt likely is total failure as soon as the tight point of the variation passes and becomes less tight.


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## keithmac (26 Dec 2019)

About all I can say now is have a Happy New Year!.


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## rogerzilla (29 Dec 2019)

For what it's worth, I had the same problem on a track bike I built up a few weeks ago (no chance to ride it yet, with the rain and salted roads). Cheap crankset, too eccentric for my liking. Filed a gnat's whisker off the tangs of the chainring, which was an unusually tight fit on the spider beforehand. Only enough so that very slight radial play could be felt with the chainring bolts done up loosely. Most chainsets have this much play out of the box.

Then found the tight spot, squeezed the two runs of the chain together very hard to pull the chainring towards the sprocket, and tightened all the bolts. Then retensioned the chain as usual. I'm very happy with it now - there is next to no tension variation and the chain can be run with no visible slack anywhere in its rotation but no binding either. It won't move; chainrings are held in position by friction, not by the steps on the spider.


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## presta (31 Dec 2019)

silva said:


> 100% disagree.
> 
> Be sure you notice it, pedaling feels like a pulsation, pushing back has a dead range due to the chain having to tension first then a shock, tensioning the chain lasts 10 times longer because you have to find the tightest spot first and keep it there in order to not have have a binding wheel and not end up ruining bearings, and it causes asymmetrical wear on the chains links, aggravating all the problems.
> 
> ...


I'm not saying you don't have a problem, I'm questioning whether anyone is making a product specifically designed to address it. I suspect not, the 'good' chanrings you've had previously may just have been lucky ones from the middle of their tolerance range. If you're sure the previous rings were made to a tighter tolerance, can you not buy more of those?


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## silva (26 Jan 2020)

rogerzilla said:


> For what it's worth, I had the same problem on a track bike I built up a few weeks ago (no chance to ride it yet, with the rain and salted roads). Cheap crankset, too eccentric for my liking. Filed a gnat's whisker off the tangs of the chainring, which was an unusually tight fit on the spider beforehand. Only enough so that very slight radial play could be felt with the chainring bolts done up loosely. Most chainsets have this much play out of the box.
> 
> Then found the tight spot, squeezed the two runs of the chain together very hard to pull the chainring towards the sprocket, and tightened all the bolts. Then retensioned the chain as usual. I'm very happy with it now - there is next to no tension variation and the chain can be run with no visible slack anywhere in its rotation but no binding either. It won't move; chainrings are held in position by friction, not by the steps on the spider.


I'm aware of centering (Sheldon Brown), and my last 2 (including current) spider also gave the chainring not any room to move (in 1 of the 2 cases I could only get it "over" the spider ridges by starting to tension bolts).
So far I didn't bother trying it, because on the first spider that did give the chainring some room to move, I sometimes noticed during riding that it moved on its mount, notably when switching from pushing forward to pushing back in order to slow down.
Meaning that the work to center it can get ruined by a first next pushback.
You say "track bike", does that mean fixed gear / no freewheel?
I very seldom use brakes, I anticipate stops and push back soon and hard enough to get there. Could make a difference.


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## silva (26 Jan 2020)

presta said:


> I'm not saying you don't have a problem, I'm questioning whether anyone is making a product specifically designed to address it. I suspect not, the 'good' chanrings you've had previously may just have been lucky ones from the middle of their tolerance range. If you're sure the previous rings were made to a tighter tolerance, can you not buy more of those?


It isn't the chainring that is offcenter, it's somewhere in the crankset.
So far I have had 3 cranksets on this new bike (first a 110 bcd Sugino XD square taper, then a 144 bcd Stronglight square taper, now a 130 bcd (144 not avail) Shimano 105 octalink 1.
The crankset of previous bike also was Shimano 105 but octalink Hollowtech.
And I can't chose it (Hollowtech) because my chainline is too big due to the bikes frame that is designed to allow 62 mm tyres and doesn't give the chainring enough clearance to achieve the min gear ratio I want.


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## rogerzilla (26 Jan 2020)

Yes, a track bike is a fixie. If the chainring moves on the spider, your stack bolts aren't tight enough. Some just don't work and the back nut spins with the front bolt (the Park tool for holding the back nut is next to useless), so you may need new ones. 

Loose chainring stack bolts are quite dangerous on any bike, but especially a fixie. The ring can buckle suddenly if it's only tightly held in place by one or two bolts.


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## silva (18 Mar 2020)

Are you sure about that not tight enough? I don't think that it's the chainring bolts tightness that keeps the ring in place, rather the notches on the spider and the circumferences of the bolt-nuts, that go into the holes of the chainring. The bolts just lock the lateral position, not the same-plane position of the chainring.
I think a chainring can only move (in the plane of its running) due to tolerances or wear of bolts/nut/holes.

Aside, today just another discovery of an awkward job of the dealer that sold the bike to me: I wanted to replace the front brake pads for the first time, he used red loctite on the thread of the bolts that fix the Magura brake modules to their common bracket. One I could losen with plenty effort, but the other just broke.
Since the remainder of the bolt is impossible to remove, new Magura mount part needed.

And last week, the other dealer that replaced the crankset, at the time and upon asking, he had said that the chainline would be about the same. Not. I already discovered it without measuring, since I now run a 1/4" internal width motorcycle chain, so the sprocket teeth have some free room sideways, I noticed that at the front sprocket they ran at the edge, and at the rear sprocket, the other edge. I measured 5 mm off. It wasn't a problem to solve, since I had 5 mm spacers (to correct the chainline for an 48T chainring based drivetrain) between rear cog and its IS brake disc mount flange, so I could remove those to correct the chainline.
But at the same time, my option to return to that 48/16 ratio, is gone, since the chainring would now hit the frame when the bottom bracket chain tensioner at its new-chain position.
Now, I can live with it, but still, its another occasion of dealers not to be trusted.


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## fossyant (18 Mar 2020)

I'd learn to Do It Yourself seeing as these issues have been going on for a year.


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## silva (19 Mar 2020)

fossyant said:


> I'd learn to Do It Yourself seeing as these issues have been going on for a year.



That's what I did. 

That was, aside of reducing wear along wider chains, a second reason to move to fixed gear.

Before I couldn't do anything. Now I can replace brake pads, pedals, chain, chainring, cog, tyre. I know what I need to order because I noted all specifications.

But a crankset, no. I wouldn't even know what to order, let alone replacing it by another system / something else.

Trouble is that they just want to deliver you whatever and whatever leftovers they have in their stock, regardless what you ask them, and only tell you at delivery time, or just not.

Last example case, already mentioned last post, that 5 mm chainline reduction, wasn't the sole crap with that Octalink 1 crankset that replacement with square taper, there was more crap:

On the evening the dealer stood at my door with it, no chainring mounted so called because he didn't find a 47t 1/8 th at his suppliers, I had to find one myself but he said that the bolts sat ready. The bolts were wrong (for double instead of single rings).

On top of that, it was a secondhand crankset, priced 80 euro. I never asked a secondhand and he never proposed either, he mounted it just like that and kept silent till the evening of delivery.


This same particular dealer, two years ago, he sold me a crap rear light, crap because it didn't work at first, for reasons I just couldn't locate. I went back with it, and he said the cable I used was too thick. And indeed, he cut off some of the thin wires and the light worked. But subsequently the problem became that the wire just felt out of the contact. Too thick pushes the contact away and too thin delivers too low clamping pressure. He then said that I could solder it. Come on lol. I ended up throwing the thing in the bin and buy a better one along the web.

And the reason I ceased to be one of his customers was more serious: my steering handlebars loosened and I barely managed to evade cars, ending up in a hedge. That was a couple minutes after I left his store, when he had replaced an original too short tube with a longer one. He sold me a too small frame, my shoes hitting front wheel when turning, heels hitting bags, knees hitting handlebars when turning, I had complained about it, and some months later he phoned me that he had found a solution, a tube from the rear position of a tandem, a leftover found in his stock, which had some rings to adjust the height. I walked back from that near-accident and at first he even laughed. I asked what now and he ended up bringing it back to what it had been when I entered, again no solution.

See, the issues I had with dealers didn't go on for a year - they went on for decades. 4 dealers. Maybe I just had bad luck but it's how it is, in my region. With this last bike / dealer I wanted to finally get rid of the crap. Therefore I asked a list of all parts of the bike, before buying. He refused saying that "the engineers needed something to work with" due to my special demands (travel bike conversion to fixed gear). Seen afterwards, I wonder about those "engineers". Whatever skills they might have had these were irrelevant - they failed and in order to get away with it still selling the bike, they kept their mouth shut about problems and lied. Delivering a bike full of problems, even design flaws alike stainless steel bolts on aluminium), for 4300 euro. It's ridiculous, yesterday I tried to replace front brake pads - I had to deflate the 62 mm tyre. And the hydraulic module, a non quick release on one side, the bolt broke in the middle before losening. On the other bolt, I saw red loctite.
In the past, the rear cogs 6 bolts were also mounted with red loctite. I had to re-tap the thread in the holes. And they were 8 mm instead of the specified 12 mm long minimum.
Two weeks riding the new bike: the chainring started to wobble and fret in the frame. Something had losened inside the bottom bracket, and after 3 weeks, first saying bearings and that I could continu riding it (I didn't, LOL) he secured it with... loctite. 
It's a travel bike, advertised as pack donkey in the mud, but nowhere grease, not on any stainless steel bolt (galvanic corrosion with aluminium) and not in the bottom bracket.

But I managed to make the bike like I wanted it to be at ordering time. Only that chain tension variation is left and it looks like I'm gonna need to live with it. My 2 previous bikes had Octalink 2, apparently those were centered / no chain tension variation. But Octalink 2 said as not available for the large chainline distance from the center.


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