dumb question-- wheel size exchangable?
 

this should be a simple question, but I can't find the answer anywhere-- can you put 700c wheels on a 70s roadbike that came with 27" wheels? I have a sick frame but the wheels must be half the total weight, it's a bit ridiculous. Or should I just cruise the garage sales and see if I can find some lighter 27"s (are they out there or mainly custom?)

700c wheels are 8mm smaller in diameter than 27". So you'll need to be able to move your brake pads down 4mm. Or buy new longer reach brakes. As for good quality 27" wheels, they are available, but not super easy to find.

Despite the reduction in braking leverage, I recommend switching from 27" to 700C rims to obtain the best possible selection and pricing on tires.

thanks, guys!

Just make sure that your brake shoes can be dropped 4mm on each wheel, and you should be good to go. Plus, that much more clearance for fenders!

harriscyclery.com will hook you up with some 27" Sun rims. I just had a set built by them with their own high-flange hubs and DT double-butted spokes. MUCH lighter than the steel wheels I took off the bike.

I'm having a set of 26" x 1 3/8 wheels made up with a Sturmey-Archer hub using new alloy rims. Not only will they be lighter but they can handle higher pressure tires. I went back and forth on whether to get the 650B's instead of the 650A's but decided not to anger the C & V Gods and stuck with the A's.

I'm already in hot water for converting inexpensive bikes into singlespeed/fixed gear rides.

Yeah, that's what I've been doing... but in a pretty amateur way.
Found a great (but scratched :-( ) old bike (69? raleigh Super Course); took the derailleurs off and shortened the chain to a gear ratio I like. But I still have all the old cogs and the heavy wheels; I'm hoping to find some lighter wheels and also be able to have spacers and just the 14t cog (aesthetics really, I hear spacers aren't much lighter). But this is all with no experience and 2 weeks picking thru sheldonbrown.com

I've never had any trouble finding adequate tires in 27", I don't know why people say that.

LBS sold me a decent alloy 27" front wheel for around $30.00. Laced a $15.00 no name alloy rim on the rear hub, and put on a pair of Conti Ultra Sports, 27x1 1/4. Much lighter and faster on my 1985 Schwinn Sprint, and better braking, too.

I can find 27" tires easy enough, but not necessarily in the width, brand, type and price that I'd like. The selection for 700c is soooo much larger.

A 14t freewheel and spacers is a lot lighter than a 5 speed freewheel, plus less ugly. If you're gonna do it (and I personally have no objection as long as people aren't grinding bits off frames), you might as well do it pretty.