cyccommute 

The HPX was good for its day...I've owned several...but the Morphs are a step above them. They are durable, the road version is capable of reaching as high a pressure or even higher, and they switch between valves in exactly the same way. However, the HPX has to be held steady or braced against something to get the pressure to north of around 80 psi and the pumping action is prone to ripping stems without bracing.

The Morphs...there are separate road and a mountain versions just like Zefal makes...don't have to be braced against a tree or your thigh and won't damage the stem because the pumping action is directed into the ground. Instead of depending on your arm strength, you can throw your body weight into pumping up the tires like a floor pump. For smaller or weaker riders, this is advantageous over the HPX.

Finally, it's not the length of the barrel that allows you to develop high pressures but the diameter. A long narrow barrel means that you can develop more pressure on a greater volume of air but that greater volume resist being pressurized more. It takes more strength to move that volume of high pressure air. Even a big guy like me finds it very difficult to pump an HPX when the pressure get over around 100 psi. I usually resorted to putting the wheel against my thigh or against an object and pumping them up that way. I could probably find dents from the pump on my leg 15+ years later

noglider 

Great endorsement, cyccommute. You sold me. I'll put that on my list.

erig007

I'm not so sure on this one.

Work = force x travel
and
force = pressure x surface

whatever the pump you choose the pressure is the same as it is the one which is after every pumping but there is also a temporary pressure created by the difference of air volume able to go through the valve to the inner tube and the air moved inside the pump chamber. So assuming that both pumps have the same tube diameter (where the air goes through the valve to the inner tube) the temporary pressure will then be higher with a bigger volume of air moved for every inch of travel of the piston but also for a bigger travel of the piston with a smaller diameter of the piston because it is the difference of flow which creates the temporary pressure not the diameter of the piston alone. Same thing apply with the negative pressure created when filling the pump with air on the way back.
So assuming people don't like to move like crazy when pumping the lower necessary travel speed being with the pump with the bigger diameter it will be easier for someone pumping to reach higher pressure with a pump having a bigger piston diameter.

So the result should be what we already know. A pump with a smaller piston diameter should means easier pumping every time but more pumping or at least more travel and a pump with a bigger piston diameter should means harder pumping every time but less travel and possibly less pumping. Why possibly because if both pumps have the same volume of the air in the chamber due to the diameter or the length of the pump then it will takes the same time to pump.
In real life though because it is easier to reach higher pressure with the pump having the bigger piston diameter and because air is a compressible fluid slightly more air should be pumped every second with the pump having the bigger diameter (PV=nRT). But because life is not easy, more travel of the piston in a pump having a smaller piston diameter means more friction and more friction means higher temperature and higher temperature means higher volume of fluid or higher pressure for the same volume but also shorter life expectancy.

When the pressure in the inner tube is higher than the temporary pressure which happen pretty fast then because force = pressure x surface then the bigger the surface (piston diameter) the higher the applied force is which also means the easier it is to pump because the only force to beat is the one created by the air pressure in the inner tube applied on the check valve. (To know if there is a check valve check if the handle of the pump move back by itself after pushing)

peterw_diy

You raise a good point about bracing. I only use the HPX on the road, after flatting, so the wheel is already off. I lay it down and put my foot below it, using the toe of a shoe to support the valve stem. This also lets me put my body weight into pumping. Problems solved.

noglider 

I think erig007 has it right. And he exposes his background to add credibility.

catonec 

muu

Got both the Road Master Blaster and the Road Morph G. The former takes time but works well even on road tires up to high PSI; Road Morph G is great for pumping tires to 60-70psi, I find it a little less useful for anything beyond that.

nelson249

This:

https://www.axiomgear.com/products/ge...enforceair-hv/

MileHighMark

Can't recommend the Lezyne mini's enough. The flexible hose will save many a valves. The pumps themselves are quite efficient given their small size.