First CO2 pump was a cheapo, non-threaded one where the cartridge is held on by a cage threaded over the cartridge. It worked perfectly the first time I used it, second time the o-ring failed where the cartridge meets the pump body and left me stranded.

Second one, a better quality louis garneau pump that accepts threaded cartridges. This one worked when I pre-filled the tube in order to fit it back on the wheel, but failed when I tried to inflate to riding pressure. This time was an o-ring again, but it was the o-ring in the spring mechanism.

Is it me? Is CO2 reliable? I'd like to find an alternative to my blackburn airstick... inflating to 100psi with this little thing is more of a workout than the ride itself.