Which brands/models chainsets / chainrings have perfect centering?
- Thread starter silva
- Start date
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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
Guru
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.
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.
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.
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.
rogerzilla
Legendary Member
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.
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.
presta
Guru
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?
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.
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.
rogerzilla
Legendary Member
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.
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.
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.
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.
fossyant
Ride It Like You Stole It!
- Location
- South Manchester
I'd learn to Do It Yourself seeing as these issues have been going on for a year. 
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.
