Monday, October 10, 2011

Wheel Repair

I'll try to explain mild to moderate wheel repairs. Machine built wheels tend to wobble after a while, especially ones with low spoke tension. I recommend buying the proper size spoke wrench before attempting repairs. A large flat screwdriver can sometimes be used to turn the top of the spoke nipple (the piece that screws the spoke onto the rim). Make any adjustments in 1/4 to 1/2 turn increments.

A wheel that suddenly starts wobbling usually means a spoke broke. Replacements can be threaded into the hub and into the existing spoke nipple. Pay attention to the wheel’s existing spoke pattern, and lace the spoke through the wheel the same way. Deflate the tire, then tighten the spoke nipple with a spoke wrench or flat screwdriver on top (remove the tire and rim strip first to use the screwdriver). Deflating the tire protects the inner tube from punctures as you turn the spoke nipple. Tighten the new spoke until the wheel spins true again. Finally, pull hard on the new spoke to stress relieve it.

Sometimes a wheel will just go out of true over bumps. A mildly warped rim can usually be corrected by increasing the tension on the spokes opposite of the bend, and decreasing the tension on the bent side. This will pull the rim back into a straight or “true” rotation. Tightening the spoke nipple increases spoke tension, loosening will reduce tension. In general you want all the spokes on one side of the wheel to have the same tension. This will result in the strongest and most stable wheel, but will not be possible with a well-used rim. In that case, do the best you can to get it straight again.

Here's some more information. Spokes are all in tension on a bike wheel. This tension distributes the rider’s weight across the entire wheel rather than just on the spokes between the axle and the ground. The rim itself is relatively weak, and needs considerable spoke tension to hold it in place. The spoke tension also needs to be balanced on each side of the wheel, otherwise the rim will wobble towards the side with more tension.

    No comments:

    Post a Comment