franked.it

Hi all,
I have a 2005 Specialized SX Trail. It has a Specialized edition 5th Element rear shock on it. I sent the shock off to Avalanche a year or two ago to have it rebuilt. I've also replaced the bearings in the frame and the frame movement seems to be quite smooth.

What I'm running into is when I am riding downhill and I hit a root or rock drop, or maybe two in a row, I'm getting a pretty stout knock or hard hit in the rear. I'm not sure if it's on compression or rebound. Also, just riding off a curb, the rear seems dead. It does compress some, and rebounds out, but does not seem to function like I expect it to.

The spring on the rear shock is the one that originally came with my bike in 2005. I was wondering if it's fatigued by now and need to be replaced?

I've adjusted the sag to 25-30%, but that takes a few turns of the preload ring after spring contact. If I do a single turn after spring contact, I am at 36% sag. The spring is a Fox steel 500x2.80. This seems to be happening with rebound fairly open or quite shut. There is a good bottom out bumper on the shaft from Avalanche.

I ran the Fox rear spring calculator, and based on my current weight, it suggested a 350 pound spring! I currently weigh 178 pounds, and usually carry 2L of water in my camelbak so probably 185 total rider weight? Based on the calculator telling me I should be running a 350-400 pound spring and my 500 pound spring requiring a few turns of the preload ring to get proper sag, I'm thinking that 500 pound spring is not acting like 500 pound any more.

Any thoughts or ways to tell if a spring is done? Thanks!

franked.it

Oh, I should mention, I've spent some time searching with Google and specifically in some forums including bikeforums and can't seem to find and answer as to when it's time to replace springs.

AnkleWork

You can measure spring rate fairly easily.