Correct, only use the nut/washer/thingy if you can't seal a pump on the stem because it's too short (can you tell from my use of proper terminology that I teach bike maintenance classes?).

Regarding presta valves in a schrader rim, I did it without the little rubber washers that LPH refers to, but I used the stem nut instead. Worked just fine and I didn't flat.

Quote Originally Posted by Beane View Post
You said "if you have to use it".. does that mean that if the stem is totally easy to get to because either it's long or the rims are shallow, I shouldn't be using the little nut?

thanks!