Truing your Rear Wheel
by physicistbiker from ThumperTalk.com
Here's my technique for truing wheels--it works pretty good.
Put the bike up on a stand so that you can spin the wheel easily. Get a spoke wrench or very small cresent (adjustable) wrench, a black sharpie marker, some solvent and a rag. Spin the wheel fast and bring the marker up to the wheel using the swingarm or something to steady your hand and the marker. The marker will make contact with the "high" points as the wheel "wobbles" by. After a couple of rotations, remove the marker and stop the wheel. Look at the wheel--it will have sections that have a line from the marker. If the line is most of the way around, you'll want to adjust the spokes in the nonmarkered area, but if there are just small areas with the line marks then adjust at the lines. If you are adjusting the lined areas tighten the spokes on the opposite side. This will pull the wheel away from the line marked (bulge) area. Use about a half turn at a time on the spoke nipple. Do this at each marked spot (or if doing the nonmarked areas its the same thing, just opposite side). Then use the solvent and rag to clean the marker off the wheel and start over. Eventually the marker should put an even line all the way around the wheel. It should then be trued. You will always get a little wobble at the point where the wheel was welded together-don't worry about that. As a final check take a small wrench and tap each spoke. You should get a similar sounding "ping" out of each one. If one or more have a "thud" then they need to be tightened. Hope this helps. Its really pretty easy.