Milton Keynes

The rim on my rear wheel started cracking apart, so I got a new wheel. Unfortunately the new wheel is drilled for Schrader valve stems instead of the Presta stems which I use. I know they make adapters to fit in the holes, but I won't be able to get back to the bike shop for a while. So what I did was screw one of the flat Presta nuts all the way down on the stem before inserting it through the hole, then another one on the outside like normal. Is there any issue in doing this, if even temporarily? I think this is a better solution than not putting anything on the inside part of the stem. I run 90 PSI in my tires so I would be afraid the stems would blow out if I didn't have anything holding them back.

phughes

Then have them delivered to your door.

https://www.amazon.com/Quad-Wheels-M...-23&th=1&psc=1

Or rubber grommet style: https://www.amazon.com/Pack-Schrader...%3D%3D&sr=8-21

Crankycrank

No issues. They were actually designed with the collar for just this purpose, and you actually only need one on the outside of the rim. As mentioned above you can order Schrader hole adapters for cheap if you like that solution better. I like the rubber ones better as they offer a little more protection against cutting the base of the valve stem.

dmark 

Continental presta tubes have a shoulder on the locknut that sits in a Schrader hole to secure the presta valve.

Troul 

A short piece of thick heat shrink [marine grade] is what I did for a rim I used in the past. I pre-installed the spare tubes I carried once I found the ideal length needed.

79pmooney

We used to use thin washers bent to the curvature of the rim. That was before the narrow center channels. Now I'd probably do the same, then grind flats on the sides of the washers so they fit in the channel. (I never did this. I was a sewup only guy.)

Chuck M 

I have had them on some Kenda tubes as well. I save them as I come across them for using on Schrader rims.

Look around on your other bikes, you may have one of the shouldered nuts on one of them you can use unless you don't use the nuts on your Presta tubes.

andrewclaus

Or don't worry about it. My wife's bike has had Presta tubes in Schrader rims for decades without an issue, with high pressure road tires.

Andrew R Stewart 

This, unless one is really bad at attaching and removing the pump valve chuck on and off the valve. Then the added support of the valve stem might reduce a valve base issue which would be caused by the wagging or twisting that some do when dealing with a pump chuck. But once aired up the PV in a SV hole needs no added support during riding. Andy

Trakhak

Bad idea, if the flat Presta nut prevents the rubber at the bottom of the valve stem from sitting flush on the rim's inner surface. The inflated tube will try to fill that gap, possibly stretching the rubber thin enough to fail.

You can pick up various diameters of rubber grommets for electrical wiring at almost any hardware store. Chances are you can find a size that fits the rim and valve perfectly.

cyccommute 

Or, even better, shouldered presta nuts. I find them easier to use than any other grommet.

JohnDThompson 

This is what to look for:

pdlamb

I've been doing this for years, albeit inadvertently. Wore out a rim, rebuilt the wheel with a new one, and didn't notice the new rim was drilled for Shrader. If I'd noticed, I'd have put on a rubber bushing, or cut a hole in the middle of a 1" square of old inner tube. But it's working fine, so if it ain't broke, why fix it?

Troul 

drill a new port for the presta valve in the rim somewhere else?

flanso 

The Continental presta valve tubes that I bought from Amazon came with shouldered presta nuts.

tcs

Some 40 years ago I had some Wolber tubes where the presta valve was held onto the rubber tube by a screwed-down nut, rather than being vulcanized/bonded onto the rubber. They would work for a bit, but eventually all became self-flatting as the rubber stressed around the nut.

DiabloScott

My first option would be to use the presta valve in the Shrader hole with no nuts. Chances are good it'll work fine and last long time.
Second option would be to use a nut or washer. Chances are you don't need it... but depends on rim/tube matchup.
If you don't have a rim-cuts-the-valve problem, the grommet won't solve anything.

I ran this setup for years - no problems except some water inside the rim during the puddle season.