au76666 writes:

On Wed, 10 Jul 2019 17:56:13 -0700, AK wrote:

I bought a package of CO2 inflator which clearly states it works on
Presta And Schrader valves.

It has nothing to depress the needle part of the inner tube valve to
allow the gas in?

Thanks,
Andy

Why, btw, is CO2 used? Why not plain air?

When compressed in an inflator cartridge CO2 becomes a liquid (or a
supercritical fluid of similar density, above 31C). This allows a
large molar amount to be stored at a reasonable pressure.

Dry air, or N2 in the product Hizzoner Scharf linked a few days ago,
behaves much like an ideal gas near room temperature even under
considerable pressure, so storing a similar molar amount of it would
require much higher pressure, and a stronger and heavier cartridge.