On most rims there's enough room to widen the hole from Presta to Schrader.
2011-09-11 12:45:58
17
ooops!!
Stopped at the bike shop yesterday to pick up a new back wheel. (mine had snapped a spoke and I wanted to get a nwe wheel and then fix the old one up as a spare.) I asked all the questions I could think of and found the new wheel I wanted.
I took the wheel home and decided to swap the cogs over this morning. This went without a hitch and I was feeling really good about the whole thing. when I got the Cog off I saw why the spoke broke. Im guessing something really bad happened when I wrecked since half the spokes (outward facing ones - the same ones that I broke) were all chewed up. So I felt really good that I was replacing the wheel and would replace all those spokes before I used the wheel again.
My good feeling didn't last, when I went to put the tube back on I noticed that the hole for the valve looked a little narrow, and sure enough it was Presta instead of schrader.
Not only do I not have any Presta Tubes but I dont think My floor pump is presta either, also my front tire is Schrader so I either have to carry two different types of tube or figure something out to use a presta tube on my front wheel as well.
any advice would be great. as it looks now I will be putting the old wheel back on my bike for the next week or so until I can get this sorted out.
2011-09-11 12:43:42
I thought about that but wasnt sure i wanted to take that risk with a new rim
2011-09-11 12:57:34
You can also use a presta tube in a schrader rim by using a little rubber grommet you can get at the LBS, and also pick up an adapter for the pump – total should be less than $2.
Or as AB suggested, just drill out the hole then sand the edges of the hole smooth. The only real risk to the new rim is if you overheat it and ruin the temper, but I think that risk is small.
Edit: Sheldon Brown's site says -If you want to convert a rim drilled for Presta valves to accept Schrader valves, drill it out with a 21/64" drill bit.
2011-09-11 13:10:33
You can't take it back?
2011-09-11 13:36:42
Do you really need a grommet to put a Presta tube in a Schrader rim? Cause I surely don't do that. I never even thought to look into it. haha... 
2011-09-11 15:55:26
On any drilled out rims that i have I always file the inside of the hole then cut a rubber washer from a old tube and slide it under the rim strip where the hole is. Also there is a good chance your pump works for both valve types. Most modern pumps have a head that unscrew and the insides flip over, one side for presta one side for schrader.
BTW the bike shop will drill it for you free of charge.
2011-09-11 17:18:00
well lets cover these things.
first Iam sure I could take it back, the whole thing was more the frustration of making sure of everything else, size rim brakes, shimano splines for the cogs, double wall rim good strong spokes, and then forgetting to even think about the valve size while I was there.
I could of easily bought a presta tube yesterday but at 8:30 am on sunday... not so much.
yes my floor pump used to have this brass adapter for presta valves which I never used and so when it got lost I never worried about replacing it.
but this has led me to a question I am almost afraid to ask. Is one style better than the other. or certain conditions where one is better than the other?
2011-09-11 18:09:57
The brass adaptors for using presta valves with Shrader pumps are available at any bike store for a buck or maybe 2.
Still most pumps don't need them. As willie says there is a flip over head. somtimes it's hard to figure out that it will work for presta.
2011-09-11 20:03:50
@dbacklover: I prefer presta now, but I still like having Schrader rims for one reason:
If I need a tube and all I can find is schrader, I'm not screwed. A plus for me who only has a bike to get around.
As for why I prefer presta... I just think it's easier to get air in. That alone makes me extremely happy.
2011-09-11 21:14:43
Im gonna pick up a couple presta tube tomorrow, put old wheel back together, its just gonna have to hold for another couple days.
My Bike and the Bus are the only ways I get around as well. Unless you could the few times I get a ride from friends or family.
2011-09-12 00:08:45
Just drill it out and stick with what you know.
2011-09-12 03:00:40
Also, this:
Everything you never wanted to know about valves.
http://urbanvelo.org/issue13/urbanvelo13_p78-79.html
2011-09-12 03:06:35
... There it is!
2011-09-12 03:47:42
I broke the valve stem off my presta tube at the trail head early on a Sunday morning, so I feel no love for Presta, but have received all the suggestions above and am cautiously giving them a second chance (path of least resistance just now, honestly). For me, "childproof" is a feature that I think shrader has better than presta, and that is a significant feature for me. For the adequately cautious, it seems to be less of an issue.
2011-09-12 12:33:03
@BradQ: Right on! Nice write-up indeed.
2011-09-12 17:36:16
Drilled out the rim last night and got it installed. everything worked out well and am riding on the new wheel.
2011-09-13 15:46:24