Wheel building query

[atlantis]

Hi !
This is a question for the people who are wheels builders and love to work on their wheels. Its a bit long pleases bear with me !
Rear Wheels.
I have been building wheels for recreation, and since I have a few bikes of my own it was nice to work on my own wheels. I have also built wheels for friends too.

Okay , current scenario is standard 700c rims middle range eg alex, , and straight gauge spokes. No fancy hubs.

My spoke calculation method seems pretty accurate and I don't land up with short or long spokes.
My findings are :-

Case 1. A friend used to break spokes on the rear wheel of his hybrid, drive side, I rebuilt his rim with new nipples and his original spokes, and brought it up to tension. (by feel), the wheel held strong and still is running good after 10 months. I checked this bike the other day with a tensiometer (park tool)and the deflection was really high. The rear drive side was showing almost 120 kgf to 180 kgf. the Non drive side was 96 kgf to 120.
Question:Now this gets me thinking, if at such high tensions the wheel stood good, then at what tension variation does one build a wheel ?

Case 2 . I built some wheels for my Surly build (w/out a tension meter)just by feel, I did not keep the tensions high and after riding her for 100 km found the non drive side spokes of the rear wheel went loose, I tensioned the wheel with a tension meter to about 130 kgf on the drive side which resulted 75 kgf on the non drive side. Then i mounted the tire which is a 700 x 41 knard, after inflating to 70psi, I rechecked the tension and found that the drive side had fallen from 130 kgf to 105 and the non drive side fell from 75 kgf to 68 kgf.
So I assumed this is what must have happened, the last time the tensions must have been good but after mounting the tire the tension went down.
Question : Has this happened with any of you as well ? Its a little confusing to keep the tension higher just to accommodate tire inflation ! !

Case 3 : I have an old decathlon bike( hybrid) which has served me well, and is still a great ride. I have been riding this bike for about 3 years, in this duration , i just broke a single spoke on the rear wheel. All good so far. The other day out of curiosity I checked the rear rim for spoke length and spoke tension , to my surprise, the spokes were very short and the manufacturer had tried to compensate it by using 16mm nipples which just hid the threads. The spoke tensions on the drive side were high at almost 170 kgf.
Question : Short spokes, too high tensions , shouldn't this wheel have issues ? I have ridden her for very long and the wheels are bullet proof !
Am i missing something here ? Whatever little I have read about wheel building just doesn't add up in these cases. Therefore I look up to you learned wheel builders and aficionado's for answers. I really love wheel building and need to make them so right .

Thanks for reading through , looking forward to your replies.

 

[Yellow Saddle]

Hi !
This is a question for the people who are wheels builders and love to work on their wheels. Its a bit long pleases bear with me !
Rear Wheels.
I have been building wheels for recreation, and since I have a few bikes of my own it was nice to work on my own wheels. I have also built wheels for friends too.

Okay , current scenario is standard 700c rims middle range eg alex, , and straight gauge spokes. No fancy hubs.

My spoke calculation method seems pretty accurate and I don't land up with short or long spokes.
My findings are :-

Case 1. A friend used to break spokes on the rear wheel of his hybrid, drive side, I rebuilt his rim with new nipples and his original spokes, and brought it up to tension. (by feel), the wheel held strong and still is running good after 10 months. I checked this bike the other day with a tensiometer (park tool)and the deflection was really high. The rear drive side was showing almost 120 kgf to 180 kgf. the Non drive side was 96 kgf to 120.
Question:Now this gets me thinking, if at such high tensions the wheel stood good, then at what tension variation does one build a wheel ?

Case 2 . I built some wheels for my Surly build (w/out a tension meter)just by feel, I did not keep the tensions high and after riding her for 100 km found the non drive side spokes of the rear wheel went loose, I tensioned the wheel with a tension meter to about 130 kgf on the drive side which resulted 75 kgf on the non drive side. Then i mounted the tire which is a 700 x 41 knard, after inflating to 70psi, I rechecked the tension and found that the drive side had fallen from 130 kgf to 105 and the non drive side fell from 75 kgf to 68 kgf.
So I assumed this is what must have happened, the last time the tensions must have been good but after mounting the tire the tension went down.
Question : Has this happened with any of you as well ? Its a little confusing to keep the tension higher just to accommodate tire inflation ! !

Case 3 : I have an old decathlon bike( hybrid) which has served me well, and is still a great ride. I have been riding this bike for about 3 years, in this duration , i just broke a single spoke on the rear wheel. All good so far. The other day out of curiosity I checked the rear rim for spoke length and spoke tension , to my surprise, the spokes were very short and the manufacturer had tried to compensate it by using 16mm nipples which just hid the threads. The spoke tensions on the drive side were high at almost 170 kgf.
Question : Short spokes, too high tensions , shouldn't this wheel have issues ? I have ridden her for very long and the wheels are bullet proof !
Am i missing something here ? Whatever little I have read about wheel building just doesn't add up in these cases. Therefore I look up to you learned wheel builders and aficionado's for answers. I really love wheel building and need to make them so right .

Thanks for reading through , looking forward to your replies.

Firstly, chuck away the tensiometer and stop fussing about the actual numbers.
Secondly, don't use the word bomb proof or bullet proof. It is meaningless and cannot warrant comment. Use words like durable for wheels that have worked for many hundreds of thousands of kilometers without trouble or strong, for wheels with an ability to carry very heavy loads. Then we can understand what you mean.

Case 1: There is always a 70% or so variance between left and right tension on a dished wheel. It cannot be any other way. Using your figures and assuming the range you quote is a reading inaccuracy (it could be variance per spoke per side but you don't say), it falls within the 70% side to side variance.
Case 2: Tyres do constrict the wheel and therefore do lower the tension somewhat. Most spoke tensiometers are so inaccurate that I cannot trust your figures for the exact reduction in tension. If you use a Wheelsmith tensiometer designed by Jobst Brandt, I'll eat my words.
Case 3: You say the spokes are short but the nipple did hide the thread. This is confusing. the only way to see if the spoke is short or not is to look inside from the tyre side and see if the spokes protrude the nipples or sit way back inside. It is impossible to comment on length otherwise.

 

[Nigeyy]

Yeah, the Park Tensiometer isn't that good, or necessary. I have one, and initially it helped with wheel builds. it was nice to have a visual rather than a tactile or audible guide. Particularly, I wouldn't trust my wheels to plucking them and listening for semi-octaves or whatever (full frank disclosure here: I'm not musically talented).

Anyway, once you get a bit of experience in, you can "feel" the spokes and know they are right. This zen-like supernatural talent (well OK, not really) isn't something you can easily describe online in a post (hence that was why I started with the Park Tool!).

Case 1: as Yellow Saddle says -the drive side is always going to be more highly tensioned.
Case 2: as Yellow Saddle says, but I'll add that it obviously sounds like you undertensioned. I'll also add many people (well, at least over here) don't bother using spoke prep or anti-seize or whatever lube on the non-drive side for this reason.
Case 3: if the nipple is longer and the spoke shorter, it really can't be by much (2-5mm maybe?). Anyway, so long as the spoke is threaded in enough (and not poking into the inner tube) I'd say you are all set. You didn't notice a difference anyway did you? Maybe a pro cyclist could tell the difference, but probably for ordinary people, I wouldn't think so.

Pretty much with spoke tension, it's dependent on quite a few variables.... For a really rough guide,if you end up with spokes consistently loosening, chances are you are under tensioned. If you end up breaking spokes regularly and/or end up with a spoke coming through the rim, chances are you are over tensioned. if you have a wheel that is consistently strong and runs true, you're golden!

 

[Spoked Wheels]

Hi !
This is a question for the people who are wheels builders and love to work on their wheels. Its a bit long pleases bear with me !
Rear Wheels.
I have been building wheels for recreation, and since I have a few bikes of my own it was nice to work on my own wheels. I have also built wheels for friends too.

Okay , current scenario is standard 700c rims middle range eg alex, , and straight gauge spokes. No fancy hubs.

My spoke calculation method seems pretty accurate and I don't land up with short or long spokes.
My findings are :-

Case 1. A friend used to break spokes on the rear wheel of his hybrid, drive side, I rebuilt his rim with new nipples and his original spokes, and brought it up to tension. (by feel), the wheel held strong and still is running good after 10 months. I checked this bike the other day with a tensiometer (park tool)and the deflection was really high. The rear drive side was showing almost 120 kgf to 180 kgf. the Non drive side was 96 kgf to 120.
Question:Now this gets me thinking, if at such high tensions the wheel stood good, then at what tension variation does one build a wheel ?

Case 2 . I built some wheels for my Surly build (w/out a tension meter)just by feel, I did not keep the tensions high and after riding her for 100 km found the non drive side spokes of the rear wheel went loose, I tensioned the wheel with a tension meter to about 130 kgf on the drive side which resulted 75 kgf on the non drive side. Then i mounted the tire which is a 700 x 41 knard, after inflating to 70psi, I rechecked the tension and found that the drive side had fallen from 130 kgf to 105 and the non drive side fell from 75 kgf to 68 kgf.
So I assumed this is what must have happened, the last time the tensions must have been good but after mounting the tire the tension went down.
Question : Has this happened with any of you as well ? Its a little confusing to keep the tension higher just to accommodate tire inflation ! !

Case 3 : I have an old decathlon bike( hybrid) which has served me well, and is still a great ride. I have been riding this bike for about 3 years, in this duration , i just broke a single spoke on the rear wheel. All good so far. The other day out of curiosity I checked the rear rim for spoke length and spoke tension , to my surprise, the spokes were very short and the manufacturer had tried to compensate it by using 16mm nipples which just hid the threads. The spoke tensions on the drive side were high at almost 170 kgf.
Question : Short spokes, too high tensions , shouldn't this wheel have issues ? I have ridden her for very long and the wheels are bullet proof !
Am i missing something here ? Whatever little I have read about wheel building just doesn't add up in these cases. Therefore I look up to you learned wheel builders and aficionado's for answers. I really love wheel building and need to make them so right .

Thanks for reading through , looking forward to your replies.

I wont tell you what to do with your tools or what words to use as I understand what you are trying to say but I will try to answer your question as best I can.

Case 1: There is always a big difference in spoke tension between the DS and NDS with a dished wheel, it depends on some of the hub dimensions. Today I built a rear wheel with a ratio of 33 to 67, Now it seems to me that your tension is all over the place, It;s quite possible to have a wheel that is perfectly true but with the tension up and down. so if you have one spoke with too much tension then there would be one or two neighbouring spokes with less than average tension. I aim for uniform tension and a 5% max variation between spokes.

Case 2: Yes, a tyre on will push the rim in very slightly and the spokes will seem as if they lost tension, 1200N, in most cases, is a good number for DS spokes. The NDS will have whatever tension (remember the ratio) but make sure the tension is as even as you possibly can get them to.

Case 3. Small wheels or wheels with short spokes will feel stiffer than larger wheels or wheels with longer spokes so I understand your description. I doubt that a factory wheel would use longer nipple to compensate for shorter spokes but it is easy to check if the spokes are too short. I would worry if the spoke thread engaged with the nipple by only a few threads.

 

[Yellow Saddle]

Pretty much with spoke tension, it's dependent on quite a few variables.... For a really rough guide,if you end up with spokes consistently loosening, chances are you are under tensioned. If you end up breaking spokes regularly and/or end up with a spoke coming through the rim, chances are you are over tensioned. if you have a wheel that is consistently strong and runs true, you're golden!

I agree with everything in your post except for highlighted section. In a bicycle wheel there is no link between spokes breaking and spoke tension whatsoever.

 

[Yellow Saddle]

Now it seems to me that your tension is all over the place, It;s quite possible to have a wheel that is perfectly true but with the tension up and down. so if you have one spoke with too much tension then there would be one or two neighbouring spokes with less than average tension. I aim for uniform tension and a 5% max variation between spokes.

Highlighted section: That is absolutely impossible. If the wheel is true, radially and axially, then all the spokes (per side) will be within a very narrow band of tension. The slight variance that you can either hear or measure with a tensiometer that doesn't change the tension when measuring and therefore has no friction like the one I mentioned in my earlier post, is due to rim imperfections. A rim is an extrusion that isn't uniform and thus not equally strong everywhere and hence, requires slight tension variations to be true.

The model you propose where a perfectly true wheel may contain one spoke with too much tension and neighbouring spokes thus compensating by having lower tension is a paradox. It is either only laterally true or radially true but not both.

May I also suggest you hide your tensiometer and stop BSing yourself about 5% variance etc. The variance is dictated by the rim's uniformity. If not, your wheels aren't true.

 

[Spoked Wheels]

Highlighted section: That is absolutely impossible. If the wheel is true, radially and axially, then all the spokes (per side) will be within a very narrow band of tension. The slight variance that you can either hear or measure with a tensiometer that doesn't change the tension when measuring and therefore has no friction like the one I mentioned in my earlier post, is due to rim imperfections. A rim is an extrusion that isn't uniform and thus not equally strong everywhere and hence, requires slight tension variations to be true.

The model you propose where a perfectly true wheel may contain one spoke with too much tension and neighbouring spokes thus compensating by having lower tension is a paradox. It is either only laterally true or radially true but not both.

May I also suggest you hide your tensiometer and stop BSing yourself about 5% variance etc. The variance is dictated by the rim's uniformity. If not, your wheels aren't true.

Yes Sir. I will try better next time.

 

[Yellow Saddle]

Yes Sir. I will try better next time.

OK, you are forgiven. But don't do it again and remember, I'm watching you.

 

[Spoked Wheels]

@atlantis Further to my post on case one:

I would check the calibration of your tensiometer.
It's very common to see a wheel that is true but with a noticeable loose spoke. Neighboring spokes would show higher tension to maintain the wheel true.

A uniform tension is the goal, not always easy to achieve because rims and spokes are not perfect but it's not difficult to achieve tolerances that are acceptable for the wheel to perform very well. I aim for 5% some people work on 10% that is a personal choice.

I don't go round the wheel tensioning spokes until they are within the 5% tolerance. When the wheel is close to completion I do randoms checks on the tension with the tension meter, 1/2 dozen spokes on each side is sufficient for me ( up to this point I have performed 2 or 3 sets of spokes tension equalizing) so the spokes tension difference will not be too large. However, it it is greater than 5% then I do one more attempt to bring it closer to my goal of 5%.

The following picture is from somebody that documents the information.

 

[Spoked Wheels]

OK, you are forgiven. But don't do it again and remember, I'm watching you.

You have earned a place in my ignore list. Of all your posts I can pick one that I found very useful information and I thank you for that. The rest is a lot of waffle with the book under your arm, patronising and with aroma of superiority. My judges are out there riding my wheels and as it happens some of them are forum members. I'm quite opened to new ideas and always trying to learn something that will make me a better builder but I have to say that nothing that you have said so far has made me change the way I build wheels.

It's quite possible to see things differently but there's no need to tell people to throw away their tools and do things your way when you don't see the point of using a tension meter. I could not see myself advising anyone to throw away their torque wrench and tighten a nut till they hear a click on their carbon frame because I don't believe in the accuracy of torque wrenches.

 

[Nigeyy]

In all fairness, I can see why you can say a tensiometer isn't needed -I've gone through the same learning process myself. My biggest problem was that I was not a tactile nor a musically inclined person -the definitive visual of a number was what (I thought) I needed. Having used it and built quite a few wheels (I think with great success aside from one wheel which is another story), I found I was using it less and less until one day I just built a wheel without even thinking about it. I know this is my personal experience, but I certainly don't think I'm any kind of wheel building genius either! However, I certainly won't go as far as to say someone should throw it away -it's all what you feel comfortable with.

It's quite possible to see things differently but there's no need to tell people to throw away their tools and do things your way when you don't see the point of using a tension meter. I could not see myself advising anyone to throw way their torque wrench and tighten a nut till the hear a click on their carbon frame because I don't believe in the accuracy of torque wrenches.

 

[Nigeyy]

I'm going to disagree with that one -I suppose theoretically if you build a wheel with extreme spoke tension and don't go over bumps or change stress in any way.... (which raises the question, how do spokes break anyway?) I had a friend whose wheel had a couple of spokes break and it certainly seemed like the spokes were way over tensioned. I reduced the tension, and no more breaking spokes -well at least last time I checked. I've also never encountered broken spokes on an undertensioned wheel either (though I've never seen a really severely undertensioned wheel either).

I agree with everything in your post except for highlighted section. In a bicycle wheel there is no link between spokes breaking and spoke tension whatsoever.

 

[Yellow Saddle]

I'm going to disagree with that one -I suppose theoretically if you build a wheel with extreme spoke tension and don't go over bumps or change stress in any way.... (which raises the question, how do spokes break anyway?) I had a friend whose wheel had a couple of spokes break and it certainly seemed like the spokes were way over tensioned. I reduced the tension, and no more breaking spokes -well at least last time I checked. I've also never encountered broken spokes on an undertensioned wheel either (though I've never seen a really severely undertensioned wheel either).

Let's start with your question first. How do spokes break? They break in fatigue. Metal fatigue just like when you take a piece of wire and bend it until it suddenly breaks. The spokes fatigue at two points - either at the elbow bend where a stress crack (formed during fatigue) sets in from the outside of the bend and gradually works its way inwards. At some point, when there is just a teensy bit of metal left, it suddenly completes the break and breaks in tension. That last little lip is the only part of the spoke that breaks in tension.

The other place they typically break is at the thread. This happens at the very first thread in the thread's root. This root is a good stress riser (place where a stress crack can start) and through cyclical changes in tension, the thread opens up like a cut in a potato crisp packet and runs through. These cuts are beautiful as if cut with a laser.

Technically a spoke can break in pure tension but that only happens through trauma of sorts, when a stick gets into the wheel. These breaks look completely different and display necking - a thinning of the wire and a cup-and-cone break.

The characteristic neck of a cup-and-cone break in a spoke that was tensioned to breaking point.

Technical jargon for threads. Spoke threads don't look like this, the roots are rounded in an attempt to prevent stress risers.

Perhaps you can see the rounded spoke thread roots in this photo. The shine is a bit deceptive.

Whenever a spoke breaks in tension, it usually damages the rim. Rims are much weaker than spokes and an over tensioned spoke thus cannot break without rim damage of sorts. That and the break's fine details tell us how spokes break.

OK, now for the question of why a wheel with spoke tension that's way high doesn't break more spokes than a wheel with spokes at a lower tension.
Tension, under a certain point known as the yield point (where the spoke under tension will yield and elongate permanently) is not a factor in fatigue. The only factor is the magnitude of change of tension with each stress cycle. Stress cycles comes once each wheel revolution. The heavier the load, the bigger the cycle and the quicker the spoke will break. Thus your conclusion that your friends spokes broke from tension is false.

Finally, spokes lose some tension when loaded, not gain tension. Therefore the bump-and-break association is also false.

 

[w00hoo_kent]

Finally, spokes lose some tension when loaded, not gain tension. Therefore the bump-and-break association is also false.

OK, I'll bite. Surely as there is a hub in the middle any spokes that are loaded and lose tension have spokes 'opposite' them that are, I guess, unloaded and gain it? I can see how 'crushing' the wheel when inflating a tyre will lose tension on all the spokes, but surely something that has a local effect on one bit of the wheel has a different effect on its counterpart?

 

[Yellow Saddle]

OK, I'll bite. Surely as there is a hub in the middle any spokes that are loaded and lose tension have spokes 'opposite' them that are, I guess, unloaded and gain it? I can see how 'crushing' the wheel when inflating a tyre will lose tension on all the spokes, but surely something that has a local effect on one bit of the wheel has a different effect on its counterpart?

I think you are visualizing the "hub hangs from the top spokes" scenario with respect to spoked wheels. This isn't how a wheel works. The only change of tension is between the hub and the road. The hub pushes against the road and the road pushes back - all via the spokes. The spokes above the hub don't come into the equation. The only spokes that are affected by a load are the two or three at the bottom of the wheel in the so-called load affected zone. The stronger the rim, the bigger the zone and vice versa.