Originally Posted by
Crank57
The liquid nitrogen thing requires clarification. When you pressurize any gas to high enough pressure, it will turn into a liquid. At very high pressure comes high temperature. This heat will be lost to the surroundings over time and a liquified pressurized gas will attain ambient temperature as long as the pressure remains constant. The problem would be when the pressure is released into a tire the heat that was lost must be replaced so the gas/liquid/container will become very cold; proportional to the pressue it was stored at. Liquid nitrogen converting back into a gas will be cpld enough to make a rubber tire freeze into something like black glass. Not good. Don't look for portable nitrogen inflators any time soon. Just not practical.
But you could look for them in the past. The cylinder mounted under the downtube of the 1958 Legnano racing bike shown here:
is a gonfleur which reportedly was filled with compressed nitrogen gas (note: no liquid). Compared to CO2 cartridges, these needed to be much larger and at higher pressure since nitrogen doesn't liquify so easily and the cylinder just contained pressurized gas. So there's a considerable weight penalty and it would be lighter to carry a pump - but the refillable pressurized cylinder would allow for faster inflation.