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Pump it to 200psi, remove pump, replace pump, subtract new reading. Now you'll know how much your pump loses.
 

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If your shock valve and pump work properly the air you hear escaping is the air pressure remaining in the tubing and gauge of the pump bleeding off the pump and not the shock. Although their is still probably a very tiny amount loss during the disconnect.

When you reconnect the pump you will see a lower pressure than when you originally disconnected it. This is because some of the air from the shocks air can is transferred back into the tube and gauge of the pump. The "loss" you are seeing in the pressure reading is actually from the shock pump increasing the volume of space the air must occupy when the pump is reattached.
 

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If your shock valve and pump work properly the air you hear escaping is the air pressure remaining in the tubing and gauge of the pump bleeding off the pump and not the shock. Although their is still probably a very tiny amount loss during the disconnect.

When you reconnect the pump you will see a lower pressure than when you originally disconnected it. This is because some of the air from the shocks air can is transferred back into the tube and gauge of the pump. The "loss" you are seeing in the pressure reading is actually from the shock pump increasing the volume of space the air must occupy when the pump is reattached.
What he said^^.
 

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What he said^^^
So when you reconnect, it gives you the pressure in your fork.
No you seem to be missing the point of 2obscura. When you reconnect the pump you will get a lower reading then what was actually in the fork/shock. This is because when you had for example 100psi in your shock and you connect the pump the volume increases and the pressure reduces to perhaps 90psi. Ok, at that moment there is 90psi in your shock but it used to be 100psi before you connected the shock.
So if you know you "lose" about 10psi when you connect your pump you can take that into account so you know there used to be 100psi on it before you connected the pump.
Also take into account that the "loss" depends on the pump you use, so dont think your friends pump gives you the same loss.
 

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Pressure loss upon disconnecting is negligible. The vast majority of air escaping comes from the pump and hose, not the shock.

When you reconnect the pump, you do lose some pressure.

So it's better just to pump until you're happy with the pressure, disconnect the pump and be done with it.
 

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I bought a Bontrager pump that blocks off air when you press a button on the hose head. When you remove the pump you lose no air. Very nifty and pretty cheap from memory.
 

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I bought this one it is simply awesome. I use for my fork,rearshock, dropper post and setting my tire pressure via a presta valve adapter.
Its a moto crossover product...
Solidly made, not too heavy to carry in my pack and"replaceable battery unlike foxes digital shock pump"
Works Connection - Digital Shock Pump - BTO Sports
Oh great, more things that needlessly require batteries.
 
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