Coil Spring Query...

Echo · May 13, 2004

It totally depends on the design of the suspension, there is no magic chart...

Bulldog · May 13, 2004

No magic answer.

Primary things to consider:
-frame
-shock
-leverage ratio
-progressive/straight/regressive ratio
-riding style
-primary terrain ridden

Secondary things to consider:
-fork
-stem
-bar height
-riding position (weight over front/center/back)

You find a calculator that can handle that you let me know.

Jm_ · May 13, 2004

there is a guy on mtbr that has made one, and it's been revamped a bunch of times, I find it to be pretty darn accurate now, and it has correction factors for falling rate desings, or bikes that use progressive shocks. It might not be what you want to be the house on, but for my bikes it works and it shouldn't be too far off for any at this point. Not an exact formula or way to do it, but it should at least get you in the ballpark.

http://forums.mtbr.com/showthread.php?t=8201&highlight=spring+weight+calculator

Enduro · May 13, 2004

Here U go...

http://www.mojo.co.uk/springs-calc.shtml

Jm_ · May 13, 2004

Originally posted by Enduro
Here U go...

http://www.mojo.co.uk/springs-calc.shtml

take a look at the one i posted, the fox one is not going to be very usefull because it doesn't take much into account.

buildyourown · May 13, 2004

I found the fox one pretty accurate. I took the numbers from my old bike (which felt good) and it was right on. I took its recommendation for my new bike and bought a spring 50lbs lower because I like a soft bike and its on a progressive. I got the spring Tuesday and it feels pretty good. I can just barley bottom it.

I would take the advice of the fox site. If you know you like the bike firm or soft go 50 up or down.

Transcend · May 13, 2004

Originally posted by Jm_
take a look at the one i posted, the fox one is not going to be very usefull because it doesn't take much into account.

the one you posted takes alot into account, and is still way off. It is recommending that i use a 250 lbs spring on my 223...i think not.

Jm_ · May 13, 2004

Originally posted by Transcend
the one you posted takes alot into account, and is still way off. It is recommending that i use a 250 lbs spring on my 223...i think not.

you did take into account the fact that your bike has a severe falling rate?

Transcend · May 13, 2004

Originally posted by Jm_
you did take into account the fact that your bike has a severe falling rate?

yes. To be more accurate it needs to also take into account the type of shock you are using. The new platform shocks require you to take a 500-100 pound lighter spring...

So with this graph, i would have taken a 150lb spring...err no. ha. I normally use a 450, on my current test setup i have a 300 and it feels EXTREMELY soft

Jm_ · May 13, 2004

rider weight 150lbs
bias 70%
rear wheel travel 9"
shock stroke 3"
Sag 33%
end coil effect 60%

Output;

Calculated spring rate 318lbs

Correct for extreme falling rate, add 100lbs, 418lbs

Correct for progressive shock, if correction for progression has already been added, subtract 50lbs, 368lbs.

Round down, 350lbs, round up, 400lbs...

Are those not "close"???

Jm_ · May 13, 2004

Originally posted by Transcend
yes. To be more accurate it needs to also take into account the type of shock you are using. The new platform shocks require you to take a 500-100 pound lighter spring...

You gotta follow the directions, the calculator says different.

I'm in the same boat as you though, my bike is a falling rate single pivot, and when I got the $$$ saved up for the curnut, i'm going to have a dramatically different shock rate than the current 550lbs I am running, despite a super low leverage ration of 2.222, it simply requires that much spring to keep from bottoming. The "calculated" spring weight is pretty close as well, although falls slightly short.

Transcend · May 13, 2004

Originally posted by Jm_
stuff

oops didnt notice there was stuff below the actual calculator.

Jm_ · May 13, 2004

maybe it's just me and the bikes that i've typed into it like my iron horse, foes and the 223, but I think it's pretty accurate. I don't even know how much you weigh, but a slight tweaking of the numbers;

rider weight 165lbs
bias 70%
rear wheel travel 9"
shock stroke 3"
Sag 30%
end coil effect 60%

output spring weight, 385

correct for extreme falling rate, 485

correct for progressive shock, 435, round up and you get 450.

We still have to stress that it is a rule of thumb or approximate thing that admittedly wont work in every case, but i think it's pretty accurate all things given.

vitox · May 13, 2004

yea i ran some numbers through that calculator, its really good

only thing is that if you know how to use all the features properly then you probably dont need a spring calculator anyway but thats a whole different issue.

Dirt Merchant · May 13, 2004

Hey Jackalope: I just replaced my newly rebuilt by FOX,
VanillaR, that came on my '01 Bullitt.....with a 5TH ELEMENT.
It cost me $100 for the rebuild in March, which is what I'd charge
you. I'm 5'10, and weigh 200lbs., and don't really think the 5TH
is really all that much better! It's approximately 7 3/4", eye to eye.
Let me know.......
Tim

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Coil Spring Query...

jackalope

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Echo

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Jm_

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Enduro

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Jm_

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buildyourown

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Transcend

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Jm_

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Transcend

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Jm_

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Jm_

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Transcend

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Jm_

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vitox

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