Originally Posted by
Scrodzilla
I've actually used them and they work quite well.
What you're describing is a non-issue because the stepped-down insert fills the extra space, making a Schrader-sized hole Presta-sized. The ones JDT posted work well too.
Also useful, Schwalbe tubes come with a threaded valve nut that has a step down built into it, as you tighten them onto the valve them they tighten themselves in place and fill the same gap Scrod's on about.
Kinda hard to see in the pic but
