I've never seen the point of CO2 inflators. I'm carrying a pump anyway, and it only takes about 3 minutes to pump up a tire, and I'm too cheap and forgetful to A) buy more CO2 and B) remember to throw away the old cartridge and replace it. I'd probably still have a spent CO2 cart next time I needed it. You'd think that cyclists wouldn't be so eager to rush to save 2 minutes, or to avoid exercise. Maybe they all have little stick arms and huge legs, so running the pump seems horribly hard. Is a little upper-body exercise and taking 2 or 3 more minutes really that distasteful?