[Quarashi]

I have an 7.875 x 2.25 DHX on my bike. My bike has 2 travel settings (6" and 7"). The stock spring has 2.3" (500lbs rate) of travel. I want to be able to use the bike well in both travel settings. I could solve this problem by getting a 400lbs x 2.3 spring in addition the spring I have now, or I could get a 2.6 x 400lbs (or what ever spring length comes stock with 2.5 stroke shock). The DHX has a lot of preload rings. If i could get the longer shock I could just simply preload it to 2.3 and get a 500lbs spring and back it out to get a 400lbs spring.
So, would it fit?

BTW: Does a spring with a higher spring rate weight more than a spring with a lower spring rate?

 

[.Danno.]

Adding preload won't turn a 400 lb/in spring into a 500 lbs/in. Preload's really just used to make minor adjustments in sag. Fox only recommends using a couple turns.

 

[Quarashi]

With a 2.6 spring I could safely preload it 0.3" (a little more than 7 1/2 turns on the preload ring) because the shock stroke is only 2.25". That would mean the spring rate would increase more than 100lbs/in with a 400lbs/in spring (0.3in x 400lbs + 400lbs/in). Please correct me if I have missed any factors.

Besides, shocks look cooler with a longer springs!

 

[Homebrew]

You can use whatever length spring you want as long as it stroke is greater than the shock stroke and it still fits in the shock body. However, it doesn't work like you're thinking. As already mentioned, adding preload doesn't change the spring rate. It's the still the same spring rate with some initial spring tension. You're not going to get a spring that works perfectly in both travel setting since it's different leverage ratios. One or the other is going to be significantly compromised if using the same spring.

And BTW, higher rate springs are thicker and do weigh more. And of course longer springs weigh more.

 

[Hardtails Are Better]

The longest spring you're going to be able to stuff in a 7.875 DHX is about 140mm long.



Just get a 400#er if that's what you need. Nothing is going to work right in both settings.

 

[.Danno.]

With a 2.6 spring I could safely preload it 0.3" (a little more than 7 1/2 turns on the preload ring) because the shock stroke is only 2.25". That would mean the spring rate would increase more than 100lbs/in with a 400lbs/in spring (0.3in x 400lbs + 400lbs/in). Please correct me if I have missed any factors.

Besides, shocks look cooler with a longer springs!

The 500 would have 10% more force at bottom out than your preloaded 400

with the 500 it's 500 X 2.25 lbs or 1125 lbs
with the 400 preloaded it's 400 X (2.25 + 0.3) lbs or 1020 lbs

Besides all that I've seen problems with shocks using heavily preloaded springs. The shock tops out really hard and can eventually pull the shaft right out of the shock. Rare, but I've seen it happen.