Originally Posted by
Marcus_Ti
Use 16g carts, not 12g--1x16g should get a 700cx2.1" tire to 30PSI. Threaded carts have less chance of loosing gas in piercing them.
You want larger cartridges than 16g for a 42 if you want to get to 70 psi, more like a 38g. I find
MSW's inflation chart to be the most accurate for figuring out what cartridge size is needed.