Mountain Biking - Trying to Air Up a Pump - Having Problems

Well I took my new RS Sid out for its debut ride the other day. I pumped it up to the appropriate pressures but it felt too squishy during the ride. I got back home and put the fork pump on it and found that the pressures had dropped about 50% from the time I aired them up. So I aired the positive and negative chambers back up and noticed something. When I take the pump off the valve there is some air that escapes, at first I just thought this was the air left in the line. But when I put the pump back on and checked the guage I noticed that the pressure has again dropped about 50%. So my question is this:

How do I remove the fork pump and keep the air from escaping? Thanks.

You don't keep the air from escaping, you just figure out how much extra air to pump in at first so it will be at the correct level when you remove the pump. A pump with a gauge is really helpful.

Can I get someone to agree with gwhunt?

You aren't lossing much air when you remove the pump, instead you are losing whats in the hose.

Everytime you attach the pump it fills with air, its enough to make a difference though it shouldn't be 50%.

I pump mine up to like 240. If I immediatly take the pump off and put it back on its at like 220 or 210.

The negative chamber on my sid doesn't hold air well, but it seems to have a very small volume as well. so If I have 200 in the negative, and attach the pump it'll be like 160 or something.

For that squishy feeling make sure your airing up the positive chamber, its the top one, higher then the negative. Make sure your sag is around a 1/3 or a quarter of the shock travel. I weigh 280 and I do about 240 in the postive and 200 in the negative, its a very firm ride.

Well my pump must be defective.....I can not take the pump off without the air escaping....even if i put 220psi (trying to get 110psi to stay in) when I take the pump off it goes down to 50psi no matter what.....whats the deal?

Valve issue?

Try borrowing a friends shock pump and see if it makes a difference. A good pump maintains the seal on the valve stem until the center pin has retracted far enough to close off the valve. If your valve is the problem, you can look for a shock pump that has an independantly retractable center pin.

Try borrowing a friends shock pump and see if it makes a difference. A good pump maintains the seal on the valve stem until the center pin has retracted far enough to close off the valve. If your valve is the problem, you can look for a shock pump that has an independantly retractable center pin.


I think that mine does have an independent retractable center pin. But when I unscrew this it lets all of the pressure out.....

I think that mine does have an independent retractable center pin. But when I unscrew this it lets all of the pressure out.....

If it does this for more than one fill valve then you have a bad pump. Maybe an o-ring is bad or missing. If it only happens with one valve, then perhaps the valve is sticking open.

Try another pump.

I tried another pump and that was my problem. POS Performance Shock Pump!!

I tried another pump and that was my problem. POS Performance Shock Pump!!
Sounds about right. At least pumps are cheap