On 2018-11-06, Emanuel Berg wrote:
When I first got the pump, I filled the chamber
to exactly 120psi. The release button and the
gauge on the RockShox suspension pump makes
this easy to do to a high degree of precision.

The other day I thought I'd try it again and
I noticed it took four strokes to get it up to
120psi again!

Is this some property of the gauge?

I have the same pump. It's a common one, resold under many
brand names, probably because it's inexpensive and works well.

Possibilities:

- loss of a small amount of air when disconnecting pump
- shock--pump pressure equalization when connecting pump
- slow leak from shock
- gauge hysteresis or inaccuracy

At a guess, I'd rate them in that order of likelihood.

--
Gregory S. Sutter Mostly Harmless

http://zer0.org/~gsutter/