Knock on wood--I have yet to have a flat while too far from home/vehicle to walk back. While outfitting my seat pack, I opted for a Co2 inflator instead of carrying a pump. How many psi can I expect from a single Co2 cartidge? Is one cartridge (per flat) enough, or does a flat take two cartrides? My tires are 700c X 25 on the road bike, and 26" X 1.95 on the Mtb bike. 100 psi and 60 psi respectivly.