DTM

Hi,
The Rockshox BAR shock fitted to my new Trek fuel 80 has a manual that tells you not to run the shock pressure outside 100 psi-300psi range. However when I have it set at minimum (100 psi) I dont think I can get it quite soft enough to get the 25% sag required. To get this I have to run it at about 85 psi, why is telling me that less than 100 psi is not good, can I do damage to it by running it too low

LowCel 

Possibly, it may allow it to bottom out too hard causing damage. By the way, you actually read the manual? That's an interesting idea.

The Great Stonk

you must be a major feather weight if your only needing 85psi.

you must remember that shocks and forks have a bedding in period, just because 100 psi is too much now doesnt mean itll be too much after a a few rides.

i have a giant trance with a fox rp3, according to the manual at my riding weight i should only be running 145psi, when new i found that about 160 psi gave optimal sag, and now after 500 miles miles of trails the ideal pressure has come to rest around the 180psi mark, i know why my pressures are high however - mainly because im running a 5 inch fork, on an 18 inch frame (im 6ft 1 and should ideally be on a 20 inch frame, but i prefer the tighter handling of the smaller frame) which means alot of seatpost is showing, meaning my weight is alot further back on the bike, meaning the rear sus takes more of my weight.

ed 

Your Trek Fuel 80 is an XC bike, right?

You should only be running around 15% sag on XC anyway. (opening up a can of worms here )

I'd say run it where you like it. I wouldn't think bottoming out is an issue for such a featherweight. If it bottoms out on your normal trail ride, add air or more compression damping.

LowCel 

I agree, it's not the most comfortable ride but I generally set mine up around 15 - 20%. It is completely user preference though.