13. How to True a Wheel
Aspects of wheel truing covered include radial, lateral, centering (or dishing) and spoke tension.
Wheel truing is a delicate procedure that requires time and patience. In this tutorial I'll try and demonstrate the many aspects as clearly as possible. Ideally you'll want to have a wheel truing stand, good lighting and a comfortable workspace.
If you don't have a truing stand, lateral, or side to side adjustments can be done using your brake pads as a guide. If truing the wheel on your bike, be sure to deflate the tire before you begin. For radial, or up and down adjustments, you can use an L-square as a guide by attaching it to your fork or frame.
It is very important to use the correct size spoke wrench to avoid stripping the spoke nipples.
Before you begin, carefully inspect your wheel for any bent or broken spokes. Make sure your hub bearings don't have any play and then carefully squeeze a drop of light oil into all of your spoke holes.
Spoke nipples have a regular right-hand thread, but that while you're truing a wheel, you will be looking at the nipple upside-down, so you have to turn the spoke wrench clockwise to loosen and counter-clockwise to tighten.
Make sure the spoke doesn't turn with the nipple, which will cause it to twist and break. If it does turn, apply some light oil to the nipple threads and try again.
If a spoke does break while you're truing, it'll shoot out the spoke hole with great force, so be careful not to place your face in line with the rim. Safety glasses are highly recommended.
To check radial alignment, place the guide near the highest point on the outer edge of your rim. Find the high spots in your rim by spinning the wheel and correct them by tightening both left and right side spokes evenly. Correct any low spots by equally loosening the spokes in the effected area.
Tighten or loosen spokes in 1/4 turn increments. For example, if the effected area spans the length of four spokes, tighten all four spokes 1/4 turn, and then tighten the middle two spokes another 1/4 turn. Then re-check the radial alignment and repeat the process as needed.
To check lateral adjustment, place the guide close to the rim sidewall and look for high spots on either side. To correct a left or right high spot, tighten the spoke that leads to the opposing hub flange and equally loosen the spoke that leads to the hub flange on the same side as the high spot.
Just like radial adjustments, tighten or loosen the spokes in 1/4 increments. Again if the effected area spans four spokes, loosen and tighten all four spokes 1/4 turn, and then loosen and tighten the middle two spokes another 1/4 turn.
Re-check the lateral alignment and re-adjust as needed. Remember that on the rear wheel, the right side spokes have a lesser angle and effect lateral movement less than the left. The left side spokes have greater angle and effect radial alignment less than right. To compensate for this difference, the right side spokes should be adjusted two turns for every turn on left.
Rims should be exactly centered between the axle nuts. To check this you can use either a dishing tool, or your frame to check the measurement on each side.
If the rim is off-center, pull it in either direction by equally tightening all of the spokes on one side 1/4 turn, and loosening all of the spokes on the other. Then check the alignment again and repeat the process until the rim is centered.
To check spoke tension, pluck each spoke in the middle and listen to the sound. On the front wheel, all of the spokes should sound the same on both sides. On the rear wheel, each side should sound slightly different, but the spokes on each side should sound the same as each other.
Most people don't have a spoke tensiometer, so it's a good idea to compare the sound of your spokes to the sound of a wheel that you already know has proper tension. Remember that spoke changes effect the whole wheel, so you might have to repeat these steps several times before it is true.
After the wheel is true you should always pre-stress the spokes and re-adjust before riding. Failure to do this could cause broken spokes later. There are two ways to do this. The first way is to squeeze together the parellel spokes on both sides of the wheel. The second method involves resting the wheel sideways on the floor and gently pushing down on both sides of the rim, all the way around the wheel in 1/8 increments.
After pre-stressing the spokes you will usually have to re-check and make some minor adjustments. If after stressing the wheel you notice that your rim is severly warped, it means that your spoke tension is too high. Loosen all of the spokes 1/2 turn and re-true the wheel.