I've not really measured the pressure, but it got MTB slicks up to the point I didn't feel any need to pump. They claim 40 psi for a fat MTB, or 120 for a skinny road. I have used the type that takes non-threaded, cartridges, but the body of that is bulky, co-incidentally, I was just looking at the Planet Bike ones at MEC and decided to pick one up next time I'm in. They use the threaded type, and thus do not have the bulky body to worry about. It would normally take one cartridge to fill a tube, but any left over is kinda hard to preserve for another tube. Now you have made me think on this, I should maybe experiment to see how well they fill Big Apples? I noticed they take more pumps to fill with a floor pump. Fortunately, they seem pretty flat resistant. I carry a pump as well, because if you get it wrong and don't have spare bottles, you're basically SOL. It does mean that if it works as advertised, the flat only delays you enough that you can make it back up, instead of having to apologize for being late. When I get my Xtracycle/Big Dummy, I'll probably carry a road morph, and not worry about CO2. With the weather here being so freakin' changeable, and other factors, I have to carry a ridiculous amount of gear, so space planning is necessary with a regular bike and panniers.