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I'm rebuilding a rear wheel with brass nipples after some aluminum nipples have failed. I have troubles centering the wheel.

The spokes are 260/266 mm DS/NDS long. The recommended spoke tension is 100 Kgf +10/-5, the rim is made out of carbon.

I'm using a TM-1 spoke tension meter, the tension of the DS spokes is at 100 Kgf, the tension on the NDS spokes is at about half that value.

The rim is off center to the NDS by almost 10 mm.

What I did: after replacing the nipples, I have tensioned the spokes evenly, removing all the slack. I then went on to true the wheel, maintaining equal spoke tension on each side during the process.

I am assuming, this is what I did wrong: I should have fully tensioned the DS spokes first, true the wheel using DS spokes alone. Only then, I should have tensioned the NDS spokes. According to [1], after tensioning the NDS spokes, it becomes impossible to move the wheel towards the DS by putting more tension on the DS spokes.

Is it correct that centering a rear wheel with differential DS/NDS spokes can not be achieved alone by putting a greater amount of tension on the DS spokes? Rather, it is crucial to fully tension and true the DS spokes first?

Thanks for any hints and explanations!

[1] Tensioning rear wheel?

1 Answer 1

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No, there are different sequences to get to the end result and they all work.

Literally bringing the DS spokes to final/full tension first works badly in practice. The reason is that the tension on them will increase by some amount when you then add the NDS tension, but predicting that amount is impractical. (There's no way this increase cannot happen; the rim is moving over to the NDS so for the same thread engagement, the DS tension will increase). In other words you'd be overshooting and then need to correct it back afterward.

The other thing about the idea of tensioning the DS fully first and trying to true the wheel with them alone is it just doesn't work because the NDS spokes will still be acting on it, and that point it doesn't do you any favors to use the tension balance of your DS spokes to respond to any errors that are being introduced on the NDS.

A lot of wheelbuilders do find their most expedient order of operations on a dished (rear or disc front) wheel is to do some number of the steeper-side tension layers up front. This plays to the fact that the other side (the NDS for a rear) moves the lateral/dish position of the rim much more for a given amount of nipple movement. For example, on a rim brake rear road wheel with optimal (first-choice) spoke length, my usual sequence is establish "ground zero" (all the nipple threads just barely covered by the nipples), then do three complete turns on the DS, then rough in the lateral and radial true, then start adding tension layers to each nipple. This sequence is good at allowing things to land where they need to be without any redundant work. For disc rears I use two complete turns on the DS instead, and for disc fronts I do one complete turn on the rotor side.

It sounds like you're on the right track and just need to dish the wheel. Lose some tension on the NDS, starting with say a 1/2 turn all around. That will move the dish a lot. Once you're almost there, like say 1mm from perfect dish, check the DS tension and see if it has like a 1/4 turn to give for it to land in the 100-110 range you want.

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  • Following your advice, I released tension on the NDS. Then I also released tension on the DS, because it had too much tension already. I repeatedly check the tension. I tensioned the DS spokes to about twice the tension of the NDS spokes. The wheel is (very close) to centered now. Thanks!
    – sebastian
    Commented Apr 25 at 9:38

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