Firmer fork spring rates: 3 alternatives, why is one better?

[mrgrabow]

OK, let's talk about fork springs. Say I need to run stiffer springs due to rider weight.

What are the reasons why we should run a truly stiffer spring weight vs adding some preload or cutting a few coils and replacing with a spacer to maintain original length?

[kawamaha]

OK, let's talk about fork springs. Say I need to run stiffer springs due to rider weight.

What are the reasons why we should run a truly stiffer spring weight vs adding some preload or cutting a few coils and replacing with a spacer to maintain original length?

a preloaded spring has not the same characteristic as a stiffer spring. you add maybe 10% at the beginning of the stroke, but at the end it will be only 3% stiffer by preloading it

you can cut some coils off of showa springs, at least old ones, but KYB springs are too short. they have approx 315mm travel before coil binding, depending on the model. if you cut off two coils they will have less than 300mm travel, which is less than the fork has.

then you will restrict your fork travel, and, you will destroy the cartridge tube, which is not designed to absorb forces you will get while bottoming.

the same for preloaded KYB springs, you will lose spring travel...

[ncmountainman]

a couple yrs back i did the math comparing a preloaded front spring(lets say .48 with 5mm preload) to a 0 preloaded heavier spring (lets say .52's) and the graph showed less initial resistance from the heavier spring w/o preload (i think it was around 3kg) for the 1st 15% of the stroke and then it crossed over into more progression.

so a stiffer spring w/less preload will have less initial harshness with more progression into the stroke,which is my preferred method:thumbsup: