My San An has felt a little harsh lately and it occurred to me that I've lost a lot of weight since last year, so this is the question.
Anybody know what spring rate is appropriate, for an 190 lb fully geared person on a 06 San Andreas Classic DHS, with the 7.5X2" shock?
I have it setup as an all mountain bike with a 130mm fork up front.

Later, Eric.

I dont have an exact answer but this spring calculator has been very accurate for me.
Hope this helps
Eric
http://www.tftunedshox.com/springcalc.htm

Thanks for the link.
I checked it out and its pretty cool. I thought the SPV recommened spring rate for a single pivot was a little low, but the single pivot recommendation for the Fox was very close.
I figured out what my problem was. I had forgotten that the spring was about 50 lbs under what I really needed, so I had compensated by running a little more pressure 150 psi in my Swinger Coil.
I lowered the pressure to 135-140 psi and it works great now.
That spring calculator, at the very bottom makes a comment about needing up to 15% more rate if you do drops. I don't do drops exactly but I do some pretty hard launches into drop-ins. I've found that if you up the spring rate like they said, to account for drops, its pretty darned accurate. The bike also pedals better and carves corners better with the slightly higher rate anyways.
A suspension engineer, that I talked to at Manitou a couple of years ago, told me they don't think you should run more than 25% sag at any time and he couldn't figure out why anyone, would set up a 6" bike with 40% sag, which uses up too much of the positive travel.
40% sag leaves a 6" bike with only 3.6" of positive travel.
In any case, I've found him to be right about that most of the time.

Later, Eric.:cornut:

A spring calculator would be specific to each rear shock, since compression damping varies between models. A shock with less compression damping would use a stiffer spring and vice versa. The number of pivots would not matter. I run about 30% sag on most my bikes most of the time to smooth out trails.

San andreas is 3.1 to 1 leverage ratio.

A spring calculator would be specific to each rear shock, since compression damping varies between models. A shock with less compression damping would use a stiffer spring and vice versa. The number of pivots would not matter. I run about 30% sag on most my bikes most of the time to smooth out trails.

San andreas is 3.1 to 1 leverage ratio.

Thats all true. My Swinger 3-way is based on the 5th element, but I have always suspected that the recommended spring rates for SPV shocks are to low. They try to compensate for the SPV by making the spring rate lower, but then the bikes seem to be more prone to bottoming on a big hit.
I have my bike set up to have about 30% sag fully loaded, with about 25% sag when the Camel Back is empty.
I've found that "Ed" the engineer is right, the Swingers work best with 25-30% sag.
Through my own experience I've found that Fox shocks have similar needs.
This applies to Trail, XC and light Freeriding.
I don't know about Downhill needs, only that they usually run a lot of sag. I don't know why though.
I was also wondering about the four bar vs single pivot spring rates in that calculator link. It seems to me that it would have more to do with leverage ratio and compression damping characteristics.

Tim, do you know of any good reading, on bicycle suspension design and setup?

Tim, do you know of any good reading, on bicycle suspension design and setup?

look around at this site, there are some set up guides:

http://www.tftunedshox.com/index.htm