One of the most important suspension settings is static sag-the amount your bike's suspension compresses when you sit on it. To set static sag, we use Race Tech mastermind Paul Thede's method, which takes into account any stiction in the components. It's best to have two friends to help-one to hold the bike while the other one measures-while you (fully dressed in your riding gear) do the compressing.
First, extend the front suspension completely. Measure from the seal wiper to the triple clamp for a conventional fork, or to the axle clamp for an inverted fork. Call this number L1. Sit on your bike in a normal riding position (or racing crouch if you're track-bound), and have one helper steady the bike. Your second helper should push down on the fork, let it extend slowly and then re-measure as before. This number is L2.
Finally, the fork should be extended by hand, settled slowly, and re-measured. This figure is L3. Halfway between L2 and L3 is where your suspension would settle if there were no friction in the system. Static sag can be calculated as follows: sag=L1-(L3+L2)/2. Repeat this process to determine the rear sag-measuring from the axle to a point directly above on the frame for each of the numbers. If you have too much or too little sag, dial in more or less (respectively) preload as needed.