Originally Posted by
Unca_Sam
Ensure you buy the right stem type. Schrader valves have a protected pin and are wider, while Presta valves have a nut on the pin and are narrower. Your tire's sidewall should tell you how large of a 26" inner tube you need, since a 17 mm wide wheel is on the narrow side for a typical 26" tire.
Another way to explain this is that the Schrader stems are the kind you have on your car.