Does changing spring rates effect optimal shim stack design?

I am riding a '12 KTM 250sx. The suspension has been set up for me but the shock spring is just too stiff. I had planned to replace the spring and carry on. But, I am curious if changing springs will create a need for adjusting the valving.

Also I am unsure what spring to buy. Right now I have a 52. I weigh about 135 without gear, and without gear my sag is at 80mm with zero preload on the spring.

Any ideas?

Thanks

Edited by 151

Your need a much lighter spring, buy one and ride it before doing any valving, you likely won't need to revalve would be my guess. Use race techs or mx techs spring calculator.

I may stand corrected here as I'm just a student of this whole suspension thing, but I believe valving has more to do with shaft speed than position or weight on the schock, so no - with correct springs the damping will just be able to do its job better and you'll get full use of the shock.

Edited by rabbityracer

Your need a much lighter spring, buy one and ride it before doing any valving, you likely won't need to revalve would be my guess. Use race techs or mx techs spring calculator.

FYI, my experience with Race Tech Spring Calculator has not been stellar. I find the RT calculator to be inaccurate. Because of this, I have purchased a couple of sets of fork springs that I had to replace. :banghead: I have had better luck calling Factory Connection and have there techs advise me on spring rates. FC has been accurate on every spring rate recommendation. Just my experience and.02.

They both will be close, you won't ever know for sure till you get the springs and measure. RT is normally on the softer end..

They both will be close, you won't ever know for sure till you get the springs and measure. RT is normally on the softer end..

Interesting. The two sets of fork springs that l purchased based off of RT spring calculator and had to replace were way to stiff. Rates determined by FC technicians were very very close to Dwight Rudders formulation for setting correct static and rider sag front and rear.

Just trying to help someone not make the same mistake I did and save some money. My mistake cost me $200. :angry:

If your setting your bike up like dwights then I could see why you needed softer springs.

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