Pedalfaster wrote: "And the big downside: you still *should* carry a pump. Yes I've been on rides where the two or three cartriges were not enough. There are a couple of CO2 devices that also function (barely!) as a mini-pump in a pinch."

Good point. Glad I'm not a weight wienie!

There are different sizes of CO2 cartridges. What is the size for a road bike?