Recently I noticed my rear rim on my MTB was out of true so had a go at truing it which I managed to do. Problem was that as soon as I started riding again it went out of true at exactly the same point as before. I tried again thinking I may have done something wrong the first time and made sure I had got the wobble out, but again, when I started riding it immediately went out of true again. I have managed to true a wheel before without problem so does anyone know what could be causing this? Is there a possibility the rim been damaged?
wheel truing problem
- Thread starter al78
- Start date
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PpPete
Legendary Member
- Location
- Chandler's Ford
Yes, but maybe not terminally.
My guess would be that none of the spokes are tight enough. So any that are holding the rim in what is now an "un-natural" position are unwinding as soon you put them through the alternate load-unload cycle (sorry poor pun) that riding on it entails.
Try truing it up, then tighten all the spokes another half turn, stress-relieve it, maybe another half or quarter turn, (might need more on DS than NDS to keep dish right) then stress-relieve it again. How hard to turn the spoke-key ? If still easy on all the spokes, more winding may be needed.
accountantpete
OAP
true the wheel again and pop a small dab of paint on the nipple and rim - that will show you if the nipple is unwinding.
Other than that - it could be that the spoke is twisting when being tightened and is untwisting when on the road.
Other than that - it could be that the spoke is twisting when being tightened and is untwisting when on the road.
GrasB
Veteran
- Location
- Nr Cambridge
To reduce spoke twisting issues when working at high spoke tension it's best to overshoot by about 50% & then back off the overshoot. Eg. turn the spoke 3/4 of a turn clockwise & then 1/4 of a turn anti-clockwise.
When you rode your bike after truing did you hear a pinging sound from the wheel. If you did that is a sign that you did not eliminate the spoke wind that occurred during truing.
Did you de-stress the spokes after truing i.e. grab pairs of spokes and give them a good squeeze? This should eliminate spoke wind up.
After you have stressed the spokes check the wheel for trueness.
Another cause could be that the spokes you have trued are under tensioned in comparison to the rest of the wheel. You can check by comparing their pitch.
Did you de-stress the spokes after truing i.e. grab pairs of spokes and give them a good squeeze? This should eliminate spoke wind up.
After you have stressed the spokes check the wheel for trueness.
Another cause could be that the spokes you have trued are under tensioned in comparison to the rest of the wheel. You can check by comparing their pitch.
Yes and yes I did forget to take into account the spokes twisting. I'll have another go with it tomorrow evening.
accountantpete
OAP
Normally the spoke un-twisting would only cause a small amount of untruing. In severe cases I have found that the nipple was bottoming out on the thread of the spoke so just check that the offending nipple isn't doing so.
