I have a 250 Sherco and I'm looking to change the front fork spring to a slightly stronger one.
I'm happy enough with the compression damping but I'm looking for a slightly stronger spring to set the front fork sag to the correct level. I'm 13 St and cannot set the sag to the recommended level (1/6th of the full travel with me on the bike) even with the pre-load adjuster screwed right down.
I'm using 5 wt fork oil and thought about going up to 7.5 wt, however this will presumably just make the fork compression and rebound slightly firmer but do nothing for the sag level. I've also considered making my own pre-load spacer for inside the fork tube out of some strong upvc piping or something similar to compress and strengthen the spring which should get the sag to the correct level.
However I'm then overly compressing the spring which reduces the static sag to less than the recommended level (about 10mm).
Looking through internet sites, there is a multitude of aftermarket fork springs available to suit almost any size. The Sherco fork spring is linear (i.e the coils are evenly spaced) but I've also seen variable rate springs, where the damping becomes progressively firmer at the end of the forks compression which seems to make more sense.
I would rather order and fit the spring myself than send the whole fork off to a suspension tuner to keep the cost down.
Anyway, my question is does anyone know the spring rate (Nm) of a standard Sherco fork spring or even a normal trials spring. It would be a handy starting point to look for other spring options.
Thanks in advance.