Spring rate

[jmross]

I need help picking a spring rate for the rear shock. I only ride sand dunes. +6 swingarm and I weigh 240lbs. I called race tech they said I need a 12.something kg/mm. That didn't sound right to me. Thanks.

Edited December 19, 2016 by jmross

[jmross]

On racetechs spring rate calculator they list a 8.12kg/mm with my weight and a +3 swingarm. Im just shocked that another 3" in swingarm length needs a spring that much stiffer.

[Sandking]

What you want is a 0900.225.0500 spring from eibach which is local to racetech and they can get it when doing a rear shock rebuild, I have it on both of my +4 swingarm bikes.

[jmross]

Just put an order in with racetech. I went with a 12.5 kg/mm or 700lb/in as per their recommendation. Had to get a set of collars with it also. I'm guessing it's a bigger diameter then the factory spring. My shock has already been re-valved too. Hopefully the valving matches well with that stiff of a spring.

[Sandking]

I had to do the collars also.

[trickedcarbine]

On racetechs spring rate calculator they list a 8.12kg/mm with my weight and a +3 swingarm. Im just shocked that another 3" in swingarm length needs a spring that much stiffer.

When you make the swing arm longer it creates more leverage on the spring. Kinda like using a 24" crow bar vs a 36" crow bar. Far more leverage. Similar principal.

[locogato11283]

FAST actually stocks and sells different springs as far as I know.