Never owned an air fork so please forgive me all the questions tonight. I have set my sag and my negative chamber 5 psi over the positive, obviously i need to get out and ride them to see if this works for me. When i check the pressure on the positive it always shows about 10psi lower than i set it (i know this is something to do with air in the pump) but when i check the pressure on the negative it shows about 40 psi less than what i set that. Is this being lost into the pump ??? or is there a fault somewhere or do i have to pump the negative back up quite a lot every time i check it? aqny help greatly appreciated
Pressure loss when you put the pump back on is due to a set amount of air in the chamber then expanding into a slightly larger volume (+ pump hose and gauge) hence less pressure.
The negative chamber on a rev is MUCH smaller than the positive therfore as a percentage of total volume the pump hose/gauge assembly is higher and so the pressure loss will always seem to be higher.
Not a problem with the fork just something to remember and dont stick in 40psi extra like some people do!
Thanks v10 thought it was something like that these forks require a lot more setting up than my vanillas did
I find that the forks start to lose travel when the negative chamber has more pressure than the positive chamber. I set mine up like this :
1) empty negative chamber or leave just a small amount of air in it.
2) Set travel to 25% sag by adjusting pressure in positive chamber.
3) Top up negative chamber until the fork begins to lose travel.
I usually find the negative chamber ends up with about 5-10psi less than the positive.
Anyone got any other ways of doing it ?
Agree with V10 about pressure loss. IMHO 25% sag is too much - manual says 15-20%. I do what is probably termed aggressive XC, and I'm happy with just under 20% sag and equal +ve and -ve pressures. Don't see why more -ve pressure reduces travel unless you go way over the +ve pressure. The -ve is only to overcome initial travel stiction.
As Keva says basically, but start with equal pressures and midway on rebound and go from there.