Rockshox Reba - how big is negative air chamber?

beelzebomb

This has been mentioned across the forum over the years bit I've never seen a definitive answer, so...

My shock pump has its own chamber, hence the sound of air escaping when it's disconnected, so I know that it's not air escaping from the chambers, but just how big is the neg chamber exactly - could it be the same size as my DNM Flamethrower pump's chamber - about a thimble size?

I ask because every time I reconnect the pump after setting the neg pressure it always reads zero, I know some air will escape into the pump chamber, but to read zero the neg chamber on my Rebas must be either leaking or pretty much the same size as my pump's air chamber.

Anyone serviced Rebas themselves and seen how big the negative chamber is?

beelzebomb

Any thoughts out there?

nicklouse

If you are getting zero then something is wrong.

Your pump chamber size depends on where the handle is. Ie it varies.

A drop of 20-25psi is normalish.

beelzebomb

Is that definitely right though? I know the neg chamber is small and I've heard so many others saying they get similar results.

coulddobetter

If my sid dual air is anything to go by then you have a knackered o ring allowing air to move into pos chamber. Same thing happening I.e neg chamber reading 0

beelzebomb

Ok, daft school boy error - I reckon I forgot to screw in the pump once the pump chamber had been connected, so I was only blowing air into the pump chamber and not the shock neg chamber as all is ok again today!