Fork springs - 0.46

[stay_upright]

For people who may have read/followed my posts in here before I revalved my 45mm marzocchi's off my 05 EC300 with a lot less base valve stiffness.

I have just modified the rebound stack stiffening it in a similar way to Pobit's findings/recommendations.

I checked the spring stiffness with an assembled leg by smearing grease down the leg, removing the air bleed screw and pushing down with my hands until all my weight was on the leg. I tried to do it gently so i am not bouncing on it. I measured travel = 175mm and then my weight on some scales = 80kg. This gave a spring rate of 0.46N/mm.

So I think the springs have been changed - right? I think 0.42 is standard?

So I'm pondering whether I should be changing the springs back to standard? With the curent compression set-up they seem to be working well and the extra stiffness in the rebound stack would be welcome.

Any thoughts? - what's the difference of stiffer springs and less compression damping vs weaker springs and more damping?

I should check the rear spring as well...

 

[rpduc]

Hmmmm, I don't know beans about measuring spring rate, but from a purely methodical standpoint I question the accuracy of your method... I never thought about measuring spring rate myself... I imagine suspension shops have a bit more "sophisticated" apparatus. But if you're determined to DIY wouldn't it be more controlled and accurate to compress the fork with a jack or long lever while it was on a (accurate) scale? Seems like that would be easy enough to rig up.

The most instructional comment on suspension set up I've seen is the "springs hold the bike up and the damping controls how the fork moves."

Wrong spring rate and you end up overcompensating with valving and clickers and the "normal" working range of the fork gets shifted to a less than optimal portion of the stroke.

The spring rate on the rear should be stamped right on the spring up towards the top and you should be able to see it without even taking the shock off. Might have to spin the spring to get a clear look at it.

 

[GMP]

Yeah, a lot of potential error in that method. If your 80kg, I think that a .46 would beat the hell out of you in the woods. My Cannondale 440, a big 4-stroke with the compression braking of a diesel truck, came with .47s and it was almost unridable stiff.

I have large hydraulic press with a pressure gauge, and I have measured shock spring rates as an experiment. Not knowing the calibration of the guage though, I don't put too much faith in the results.

 

[iancp5]

You need the right springs for your weight or the bike will simply not handle well. You can't really compensate with clickers for a spring that is a long way out. You can make it tolerable but never good. If I was you I'd leave valving alone until you have the right spring rates and played with the clickers. Although if Pobit's valving is as good as his jetting it's probably worth considering. All the same get the right springs because his valving will expect it as well.

 

[gaspipe]

You have to get the sag right with the correct spring and preload. That's where to start. A light spring with too much preload will yield a crappy ride, and a heavy spring with too little preload will also not work well. Get the springs right first. Then revalve if you're unhappy with the action.