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-   -   Trueing a Wheel that is Slightly out of Round? (https://www.bikeforums.net/bicycle-mechanics/554691-trueing-wheel-slightly-out-round.html)

tandemnh 06-23-09 09:21 AM

Trueing a Wheel that is Slightly out of Round?
 
I just got for father's day the Park Tool high end Trueing stand from my son (great gift, greater son!). Of course I immediately starting trueing every wheel in sight, even invited the neighbors to bring over their wheels too!

My question is, I noticed that after getting the wheels trued side to side, some wheels/rims appearred to be slightly out of round. Is there a simple way to get the rim round again? Does it matter, will the flex in the tire compensate for this or should I be concerned riding a rim that is not perfectly round. I never really thought to much about it until I went crazy trueing.

Panthers007 06-23-09 09:26 AM

If the out-of-round is a 'blip' upward - tighten 1/4 -turn the 2 spokes directly under the blip. If under - loosen 1/4-turn. Then re-true and stress the wheel. Check again on your TS-2.

I suggest that you do some research before truing other folk's wheels.

tandemnh 06-23-09 09:32 AM

Sounds good. I found it on two of the wheels and before I went to far I thought best to ask. They are minor and spinning the wheel on the bike they were not noticable, it was on the stand while I was closely eyeing the wheel that I discover the issue.

I'll give it a try this evening. thanks

wmodavis 06-23-09 10:02 AM

I highly recommend Wheel Pro's book found at http://www.wheelpro.co.uk/wheelbuilding/book.php.
It will help with all sorts of those types of questions including details on your specific radial truing question. It is a very good accessory to your new truing stand!

AEO 06-23-09 10:02 AM

if it's within 1~2mm, then it's ok.

Paniolo 06-23-09 10:15 AM

I will generally try to deal with any hops first, then move on to the sideways true. Also, since you can move the rim by either tensioning one side or by loosening the opposite side, be aware of the tension on the surrounding spokes. If you do not have a tension meter, try plucking the spokes. Ideally the spokes on a each given side will have the same tension ... or make the same tone when plucked.

Example: you need to move a section of the rear wheel left, towards the non drive side (nds). You pluck the nds spokes and they are all about the same tone. Then you pluck the drive side and in the area you want to move they are noticeably higher pitched than the others on the ds. You would want to true the rim by loosening the ds spoke rather than by tightening the nds more.

Its not rocket science ... but low spoke count wheels can be a real pain.

tandemnh 06-23-09 10:37 AM

[QUOTE=Paniolo;9151610] Also, since you can move the rim by either tensioning one side or by loosening the opposite side, be aware of the tension on the surrounding spokes. If you do not have a tension meter, try plucking the spokes. QUOTE]

tension meter and suggestions?

Al1943 06-23-09 10:41 AM

If the rim is bent you need to deal with that before truing.
It's best to do the radial truing and most of the dishing with the tire and tube off the wheel before doing the lateral truing.
The final dishing and lateral truing need to be done with the tire fully inflated.

Al

jollysnowman 06-23-09 11:13 AM


Originally Posted by Al1943 (Post 9151790)
The final dishing and lateral truing need to be done with the tire fully inflated.

Noob question + potential thread hijack (sorry in advance!): why?

Al1943 06-23-09 11:32 AM


Originally Posted by jollysnowman (Post 9152006)
Noob question + potential thread hijack (sorry in advance!): why?

This is a little OT.
The air pressure reduces the spoke tension. Most rear wheels have a significant tension differential from one side to the other due to the hub flange offset that makes room for the cassette. The differential will cause the dish to change a bit with the change in air pressure. Uneven tension on either side of a wheel can cause some lateral movement with a change in air pressure.
These changes should be fairly minor and how much change occurs will depend on how much air pressure is in the tire and how rigid the rim is and there are probably other variables.
My rims are light and I run 118 psi in my rear tires. I was surprised at how much the air pressure reduced the measured spoke tension, about one deflection unit on my Park tension meter. And the rim moved laterally about 1/2 mm.

AEO 06-23-09 11:33 AM


Originally Posted by jollysnowman (Post 9152006)
Noob question + potential thread hijack (sorry in advance!): why?

inflated tube will compress the rim (minor) and the tire itself isn't perfectly round.

tandemnh 06-24-09 09:04 PM

After reading the advice on this blog I went donw and was able to get a wheel back into round (at least very close) and retrued.

Thanks for the input. Next step is to buy a wheel building book and start from the beginning to understand how to build a wheel, so fixing will be easier.

Panthers007 06-24-09 09:57 PM

Here's one article you can download:

http://sheldonbrown.com/wheelbuild.html

And there is the venerable Jobst Brandt and his seminal "The Bicycle Wheel." Which also goes into the theoretical.

And a good online book for purchase resides over this link:

http://www.wheelpro.co.uk/wheelbuilding/book.php

Good plan - and every success to you! Enjoy your TS-2.


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