> If you're looking for tubes with a Presta valve, simply get
> tubes that would fit 700c x 21. If the rims take
> Schraeder valves... don't know what to tell you there.
If the rim is drilled for Shraeder valves (which would be unlikely - though not impossible - for a 7/8" wide rim) you would use an adapter such as this:
http://www.bikeman.com/
You can actually find the appropriate grommets at the hardware store or Radio Shack. It's not really a problem.
Fred Rednor - Arlington, Virginia (USA)