Bicycle Mechanics - what to do about a spoke that wasn't crossed in build?
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07-03-11, 01:31 PM
I thought I was hearing some strange noises from my rear wheel, so I put it on the truing stand to see what was up. It was still true, but I was shocked to realize that I hadn't crossed one of the spokes. It is a 32 hole Velocity Synergy. Many thousands of miles on this wheel.
I am tempted just to loosen it and cross it. The purist in me says to loosen the whole wheel. It's on the NDS, which probably explains why it didn't have much effect.
07-03-11, 01:56 PM
Since you can replace a broken spoke without loosening all the other spokes, then simply removing and replacing that spoke shouldn't be a problem at all. But I've wondered how much crossing the spokes really matters.
Sometimes it's best to leave bad enough alone. The wheel has thousands of miles on it with no problem, and if you hadn't looked might easily have thousands more.
But since you looked, and probably can't live with this blemish, simply loosen one of the uncrossed spokes (the outer is easier), slip it under it's mate and bring it back to true. Since this is a NDS spoke with only about 60-70% of the tension of it's neighbors there'll be no consequence to this method.
If you're a total purist you can do this in the frame, with a wedge between the drive side and chainstay at the spoke so the rim can't move over raising the load on neighboring spokes. It's totally unnecessary to do it this way, but if you're unduly concerned and considering loosening the whole wheel, this should satisfy any purist cravings, saving you unnecessary work.
No big deal, just pull it out, lace it back in correctly, true and tension the wheel.
..But I've wondered how much crossing the spokes really matters.
I did too, until I built an uncrossed wheel. It buzzes and vibrates at speed. Can't get a reflector to stick between the spokes either.
The interlacing of the inner over the outer does make a difference, though it's small.
First of all it shortens the free length raising the resonant frequency and reducing vibration. It also brings the inner and outer spokes into line reducing air turbulence and drag.
Lastly it bends each spoke slightly off the straight line, which allows some transference of stress between the paired spokes making the wheel somewhat more resilient and improving the service life a bit.
Overall all the benefits are small, but the method has proven itself over decades which is why it's standard practice.
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