Originally Posted by
SwampDude
I'm not using CO2 for topping off, just on-the-road flat repair to avoid carrying a pump. My floor pump is for keeping pressure up before each ride. I've never computed the cost of CO2/cylinder because I don't use many of them. I didn't realize CO2 escapes the tube faster than air, but it always gets me home to my old faithful floor pump.
OK but the OP is looking for a way to top off his tires routinely without buying more floor pumps so that's why I conluded you were recommending CO2 for that use. I also use CO2 for road-side flat repairs and the cost isn't a big deal since (knock wood) I don't have to do it very often.
CO2 does diffuse out faster than air but it's not important over a matter of hours, just days. When I use a CO2 cartridge to inflate a replacement tube, I deflate the tire after I get home and refill it with my floor pump.