If you are hard on valve stems this is your huckleberry. The bad-it takes around 200 strokes to a 700x23 tire up to around 100 psi. It is a little time consuming to use. You have to unscrew the hose from inside the pump barrel, then screw it onto the opposing end. Then you have to screw the hose onto the presta valve stem of the tube (easier to screw the hose on first, then screw the hose onto the pump). There is a lot of screwing going on here. The bad- if you have tubes with removable valve stems it will unscrew the stem when you go to unscrew the hose, then babe, you got no air. A little touch of loctite will solve that problem. However-I cheat. I use my road drive to seat the tire, inflate to 40 psi or so, then finish off with co2. In a pinch the road drive will work fine as long as you have strong arms and are have ride buds who are patient while you are messing with your flat tire. Some guys swear by this pump. I just like to change my flats pronto and get under way.