Old 06-03-21, 11:06 AM
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cyccommute 
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Another wall of overkill essentially based on nothing.

Originally Posted by adipe
when truing wheels you need to pay attention to radial runout on each spot of the rim (at each spoke). as i said in another thread... radial runout at each spoke.
Why? What reason do you have that this is sooooo important? Will it result in a stronger more durable wheel and what evidence do you have for your claims?

adjusting radial runout is best done at roughly medium DS tension with NDS (non drive side) spokes having almost zero tension. you just need to add a tiny bit of tension on the NDS so that you have good enough lateral true when adjusting that very important radial true and also balancing it out with spoke tension variance.
This is not bad advice for what it is worth. Doing adjustments to both lateral and radial true are far easier at low tension. But that doesn’t mean that corrections can’t be made at higher tension.

you should not aim for absolute zero radial true if that means you don't have uniform tension on those DS spokes. that is because spokes stretch under tension.
Huh?

very few wheelbuilders are skilled enough to do this balancing of tension variance with radial true without the use of any computing device. even if they have tons of experience they won't always reach the optimal build but will either be lucky and some of their work will be sloppy for the sake of expediency.
Very few wheel builders have ever used a computing device to build wheels. People have been building wire spoked wheels for close to 125 years. Computing devices have only been available widely for 30 to 40 years. Somehow, people were able to build wheels that were strong, durable, and capable of moving a bike down the road without falling apart. Even today, few people actually use a computer program of any kind to build wheels and still manage to cobble together a workable wheel.

And, here’s a clue for you, no computer program would be able to do jack crap without data from someone building wheels. Modelers like to say that there is nothing wrong with their models but they have it wrong way around. There is nothing right with their models without real world testing. All models are wrong. Some are useful.

an example:
for 2mm spokes with 290mm length and +/-13kgf tension variance you will have +/-0.04mm spoke length.
And why do I need a computer to tell me that? And what is the computer going to tell me about how to go about fixing the problem? Let’s not forget that the rim compresses up to 0.2mm when the spoke is weighted which makes that ±0.04mm variance unimportant.

having a truing stand with no dials to show the amount of radial true at each spoke means you need to work a lot to achieve almost zero radial true (less than that 0.04mm) and then you should take note of each spoke's tension to have some adjustments made after that radial runout was taken care of. if the tension variance is small enough then you are lucky with a rim that is almost perfect from the factory. having to work with a damaged rim... a cheap truing stand won't really help much.
To put your radial true measurements in perspective, that slightly less than the average human hair...0.06mm. Again, what purpose is served by your insistence on that level of runout? You can spend hours on tweaking a wheel to perfection but what do you get out of it? Park doesn’t call for anywhere near that kind of precision. They say

KNOWING WHEN TO STOP

“How radially true is true enough” is equally as subjective as lateral truing, and is subject to a few additional factors. Most significantly: the wheel will have a tire on it, and tires are not often made to such tight tolerances.

As a general guideline, 1 millimeter or less of radial deviation is an acceptable measurement. 1mm is about 10 sheets of typical printing paper. Use this as a feeler gauge to help you visualize what 1mm looks like.
For radial, they suggest 0.5mm. Their radial true suggestions are 16 times less precise than you suggest. I would trust them over some guy on the internet how doesn’t have any data to back up his ideas.

a professional truing stand would have some dials to show radial runout on any part of the rim so that you would assess spoke tension one way or another and find the compromise. with practice you could do without any computing device that you could have worked with while you don't have experience in assessing tension variance with your ear alone and everything else. plucking the spokes will not give you accurate and complete information, especially if you haven't checked with numbers what your ear tells you. you could resort to a tension meter or a tone generator but you also need to have the elastic modulus concept applied while you work with numbers. if you don't do that then you will have sloppy work. sometimes you will have a lucky build, sometimes not.
And, yet, the vast majority of professional truing stands don’t have...nor have they ever had...dial indicators but, somehow, we have been able to make workable, strong, and durable wheels. Here’s a hint: It’s not “luck”.

my first time i worked on a wheel - repairing it - i resorted to zip ties and optics for assessing radial runout at each spoke (deviation from the mean distance). i had a zip tie move and another zip tie fixed at a small distance and i used a paper on the window to have a rough estimation of the radial runout at each spoke. what i did was moving my head/eye to find where the aligned zip ties were pointing on the paper i had fixed on that paper on the window. i measured the thickness of the tapes i put on the rim where the flat spot was to have the max radial runout and then did all the adjustments with tension values noted down. very tedious work. i won't ever afford a professional truing stand so i'll always go with such a process because i don't want wheels built/repaired by so called professional mechanics and i also want resilient wheels (not only very very low lateral and radial runout) so i don't need to ever spend time repairing them once i'm done all that work.
And how many hundreds of wheels have you built? I know you won’t answer (he has me on ignore) but perhaps someone else will ask the question.
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