This is an old road bike? A modern road hub will be spaced at 130mm, there will be more available in pre-built wheels in 700c with this spacing than with a 135mm hub, as 135mm is the norm for mountain bikes. There are 700c wheels available with 135mm hubs, though, if that's what you want to do, or you could always build your own............If you go with a 130mm hub, you can either spread the stays a little by hand each time you install the rear wheel (squeezing it in, since it's only 4mm difference), or you can cold set the rear triangle so that wheel changes are easier. There are excellent instructions for cold setting on Sheldon Brown's site, under "frame spacing", I believe. If you go from 126mm to 135mm, you'll need to cold set it...............As for the threaded to threadless conversion, by far the cheapest way to go on that would be to get a threaded to threadless adapapter, which would allow you to use a threadless stem with your current threaded fork and headset. Otherwise, you'll need a new fork, headset, and stem. Here's a link to an adapter that Nashbar carries, they have models that will go from either 1" or 1 1/8" threaded to 1 1/8" threadless: http://www.nashbar.com/profile.cfm?c...9755&storetype
One more thing, if you currently have 27" wheels, you'll need an additional 4mm of brake reach to reach 700c rims, as the 700c's have a 4mm smaller radius than 27's.
Last edited by well biked; 09-21-06 at 10:26 PM.