With a sore ass
Fat guy, on a little Cannondale.....
245lbs, 5'11"; about what air pressure should I be running in my F600's Headshock? LBS is saying start at about 100#s; good idea? More? Less? No big drops or anything extreme, just want a little give to keep the Al frame from beating me up.
If you haven't done so already, post this up in the Cannondale forum as well.
Also, if you go to Cannondale's web site, in the tech section, they should have set-up pdfs for the different forks. From there you can determine air pressure.
I had the "D" air cartridge in an 80mm Headshock (Super Fatty) and used to run well over 200psi. Usually at least 220psi up to about 240psi and had no issues. At the time, I weighed about the same as you.
[SIZE=2]Assuming you have your own pump, you could try the ty-wrap method. It's simple and gives you a good idea about where the shock should be set. I use a 100mm fork (SR Suntour Axon), but I am pretty sure the travel won't effect this set-up.
Snugly (so it moves but not on it's own) attach a ty-wrap to one of the stanchions (the part that moves inside of the cartridge) and push it down to the seal. Carefully, mount then dismount the bike while trying to keep up/down bounce movements to a minimum. Be sure to replicate your riding position/posture while keeping still. After you dismount, you'll notice the ty-wrap moved away from the cartridge. Measure the distance between the ty-wrap and the fork seal. 1" should be plush; 5/8" should be firm. Adjust air pressure to your liking.
I like a firmer feel as it handles better but everyone is different and, therefore, not everyone should use the mfg pressure suggestions even though those figures will get you in the ballpark. I am 215 lbs. and my fork suggested 105# - this was very close to my desired setting of 110#. I've tried 120# and it "felt locked-out", so a difference of 5-10# is huge.
I hope this helps.