Rookie question: I've got one of the kits that has a CO2 cylinder in it for pumping up a tyre, but no indication of how will be used. Any guidance for a 700x28 tyre?
Cartridges come in different sizes – 12g, 16g or 25g. The smaller ones are designed for filling tires up to about 90 PSI. The larger ones are designed for filling tires up to 120+ PSI. This corresponds to lower pressure tubes such as clinchers (typically 90-120PSI) and tubular’s (140-170 PSI) such as race wheels.
credit to DC rainmaker, full content here : https://www.dcrainmaker.com/2008/08/how-to-use-co2-for-cycling-beginners...
Because they freeze when used, you rarely get all the gas out of one. In my personal experience, a threaded 16 gr cartridge will fill a 25 mm tyre to 'useable' pressure with a bit of CO2 left over when you get home which you have to dump to take the cartridge off.
I find a 16g cartridge easily takes my 25mm tyres to 100 psi with plenty left over.
Yep, a 16gr will do my 25mm tyres to around 95 psi with a wee bit left over so a full 16gr should do your 28s. I find the pressure drops pretty rapidly with CO2 (down to 50% within a day) so as soon as I'm home I empty the tube and just pump it up normally.
Good point Dave. CO2 diffuses through rubber quite quickly so always remember to let all the CO2 out when you get home and pump up with air.