Is it possible given the rim has a bigger hole? Maybe a larger diameter screw washer? I’ve just picked up my new steed and it has Schrader valves whereas my other bike has Presta and my spare tubes are Presta too. I could just carry a couple oversized screw washers with me. Cheers.

You can use THESE.

Mavic supply a small plastic inset to do this, I have just used the locking nut done up tight. In the end of the day schrader is better anyway so just get on with it and replace with proper tubes when you get new ones.

Why is schrader better ?
I’ve never had an issue with presta valves

bigger, easier to hold, harder to bend, works with cold fingers etc. Personal preferences is all rims schrader so you don’t get stuck turning down a tube in an emergency.

[Insert Long 6 page debate here]

I shall give you last point

Conti innertubes come supplied with a stepped lock ring to suit this very need.

I take an old presta tube, rip the valve cleanly out, cut a 2cm square out around the ‘ole, and then use that as a sort of dental dam around the new one.

Or something.

Corn plaster?

You can also get a rubber grommet to convert like this.

And it looks like you can get the adapter nuts aftermarket as well, but certainly not cheap

Am I alone in wondering why this is a problem anyway?
I’ve run presta tubes in Schrader drilled rims for years without any fancy grommets or adaptors
Certainly for an ’emergency’ tube replacement mid ride you would be fine
The other way round however….

Schwalbe tubes come with the adapter nut as standard http://wallbike.com/blog/2009/02/20/schwalbes-super-stem/ I love these tubes, its amazing how much work has gone into them seriously.

Am I alone in wondering why this is a problem anyway?

In a generous hole size the tube can move round more under larger forces and rip the valve off. Problem solved by using schraders 🙂

Like I said mike, not a problem I have encountered in 15+ years

fair enough, seen it more when people have run lower pressures, normally on a loaner tube after several problems and not putting enough pressure into it.

Whilst I agree it’s not much of a problem the holes in my rims are pretty sharp so wanted to do the same.

Mavic adapters available here for buttons:

http://www.ukbikestore.co.uk/product/59/rt20/mavic-schreader-presta-rim-hole-adapters-10-pack.html

Email me your address and I’ll pop two in the post to you.

Thanks all and especially to Ados, for the kind offer, it’s much appreciated, but I’ve sorted myself out with a couple from my lbs who were happy to donate me a couple.

I know I might have been able to get away without using them, but I’d rather have them than not.