Presta valve in a Schrader rim hole: How to use / do I need a rim hole reducer? I have a road bike here with 622-16 wheels and Schrader valves. As I needed to replace a tube, I found that most options in the 622-23 size use Presta valves.
I read around a bit and found people suggesting rim hole reducers as in Can I use a Presta tube in a Schrader rim? among other places.

This didn't sound too hard, so I went ahead and ordered Presta tubes along with these Mavic reducers.



Now that I have all parts in front of me, things are not as foolproof as I thought they would be. For one, the reducers are not symmetrical and can be inserted into the rim from either side. However, neither side feels like the clear choice. Rather, relying on the fixing nut of the valve alone seems not to be bad. Let me illustrate.

Hole reducer from the outside:



From the outside the reducer fits snugly, but on the inside it creates a bulge that the tube needs to wrap around.

From the inside, the hole reducer doesn't really fit, however. I might not be pressing it in hard enough, but in this way the valve does not get through.


Finally, I could just forgo the hole reducer. The valve comes with a nut that fits the drilled hole snugly. Is this sufficient to prevent the tube hernia mentioned in Can I use a Presta tube in a Schrader rim? ?


What's my best option here? Do I have to get another set of grommets or should I just stick to Schrader valves in this rim even though the choices are few?
With the Mavic adapters, the lip is supposed to go on the outside. They're not intended for use with single wall rims, hence the problem you're having.

On a single wall rim like yours with the relatively deep, narrow channel in the rim well between the reinforcing sections, none of the reducer grommets available are going to work very well. The other option are the aluminum ones, which are usually superior, but they install on the inside and here they wouldn't work.

Those Presta nuts that sink into a Schrader hole are bad news. They do nothing to prevent the core problem of Presta tubes in Schrader holes, which is stress around the valve from not being supported by the rim eventually causing the tube to rupture. Maybe on a single wall rim this is less of an issue, but I still don't like it.

Just use Schrader tubes. 700x23-25 / 27x1 SV tubes are perfectly common.