I’m probably flirting with danger here, but it’s been awhile since I’ve flatted.
Even so, I try to be ready if it should happen. My seat bag has a spare tube, a patch kit, and what I would most likely use in the event of a flat — a CO2 inflator and several CO2 cartridges.
The CO2 is convenient, but it’s not a panacea. When I have flatted in the past, I’ve found it’s not easy to get the right amount of air into the tire. I’ve resorted to a series of short bursts on the inflator trigger, and try to determine by feeling the tire whether it’s got enough pressure. When I first started using it, at a time when flats were much more frequent, I sometimes wasted a cartridge and needed two to fill the tire. And sometimes, I only managed to inflate the tire enough to make it home.
Another concern is the cost. The cartridges run about $3.50 each, so if one or two are wasted by fumbling around, the tire repair is suddenly costly. I usually carry four in my seat bag, so I can give one or two to another biker who might be flatted with no air.
Then there’s the environmental issue. Carbon dioxide is a greenhouse gas. Do I really need to contribute to the Earth’s problems?
What’s the alternative? A pump. The choice is between a frame-mounted pump and a mini-pump that can mount to a frame or even fit in your jersey pocket.


The issue with the pumps is also one of convenience, and efficiency, too. I’ve had occasion to use a mini-pump, and I’m not crazy about them. They have trouble supplying enough air pressure, especially to a road tire that may take over 125 psi. But I like the convenience of the CO2 inflator, and I’m not sure if another gizmo fastened to my bike frame would be worth the bother.
For now, I’ll continue to go with the cartridges and inflator. I’ve had enough experience with them that I’m confident I won’t waste them in future situations. And for every day that I go without a flat, cost becomes less of an issue. But I’d sure like to hear your opinion. Inflator or pump?
(Since this post last July, I’ve resolved the issue to my satisfaction. Here’s what I decided.)