TexKDX

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Aug 8, 1999
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Matt -

In theory, you could say they are the same, in that the fork will compress a certain amount under its own weight and then more under yours.

Unfortunately the forks don't have a screw adjuster to set the preload like the shock does. To set the fork spring preload you have to pull the caps off and change the length of the shim between the spring and the spring retainer. Doing so would have a marginal effect on correcting the bike's imbalance in spring rates front to back, just as adding a bunch of preload to the rear won't make up for too weak of a rear spring for your weight if that were the case (say you weighed 220 lbs).

If it were me, and I were going to take the time to do disassembly on the forks to play with the preload, then I'd go ahead and make sure I had good oil of the right amount in there and the correct springs. The stock oil is probably ready for a change, and the correct way to set the level is with the forks off the bike and the springs removed. By just pulling a few more bolts (front wheel, lower clamp pinch bolts, brake caliper) you can have the fork legs off and in your hands. It is much easier to work with them this way.

If you do decide to put front springs in, talk to the person you get the springs from for a spec on preload. Generally the springs need to be compressed 1/4" to 3/8". That is, when you go to put the spring retainer back on, there should not be a gap between the spring and the retainer. If the spring just barely holds the retainer on, then cut shims about 1/4" out of the provided shim material or PVC pipe.

Some springs require big shims, others no shims or small shims, depending on the fork and spring rate. I think CDave's tech tips goes over this on justkdx specific to the KDX, but for some reason when I try to access this page it comes up page not found.
 
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