My mountain bike has a presta valve on the front wheel and a Schrader on the rear. Last time I had a flat the inner tube I had at hand was a Presta valve so that is what I used with the suitable grommet. My floor pump can do both types of valve without having to change anything. I have Presta valves on the touring bike despite the fact that the rims are drilled for schrader. Means that I can use any suitable size inner tube if I am out on tour. Schrader valves are a bit harder to inflate, especially with a frame pump. Road bikes are all Presta