Bicycle pump pressure

The only way I can see with it being different is the fact that a bicycle tyre is flexible, most of the pressure switches etc are of much lower flexibilty- hence the volume of the pressure switch would remain almost the same, whereas the tyre volume has a chance to expand Does that seem sensible?

Just the larger volume of the inner tube is enough to explain it . the check valve on the pump releases some ** ccs after the last stroke The lost cc's are a much smaller part of inner tubes total volume, than the pressure switches lost cc - total volume ratio. Garth

Good call, I would have to agree. Solution, implement a buffer/tank to simulate tyre conditions.
I would also question the pumps capability to pressureize to 11barg unless i saw it with my own eyes. I don't know of any bicycle tyres that will survive 11bar

95-150 psi was pretty standard pressure for sew-up racing tires in the 60's and 70's. With improvements in materials I don't see another 15 psig being a problem.

Garth is right. If you can add a reservoir (small tank) you would get the same effect as the tire. Have you checked the instantaneous pressure level at the end of your stroke? I will bet that it peaks at or near the same as on your tire, but quickly reduces when you stop pumping due to small leaks in the system. Placing a non-return (check) valve in-line would also help, as you noted with the tire. It is probably not the diaphragm devices themselves which leak, but your pump, and the connections.

Keep in mind that check valves have a pressure drop associated with them. For static pressure in the forward direction, some schrader valves can have around 40psi on them before they open. This reduces when air is flowing through it and it's already open, but keep this in mind as well to choose your check valves carefully if you do use them.