I want to install brake calipers at the front only; sometimes I can find ones for the rear for sale. I can't see any diffs going by photos; is there any difference between front & rear calipers that I won't be able to use a rear one at the front?

The mounting bolt for a front brake is significantly longer than the one for a rear brake. The bolt has to reach across the fork crown which is much wider than the rear brake bridge. You could change the mounting bolt on a rear but that is a fair bit of work and the bolts aren't particularly cheap.

BTW, Nashbar sells their housebrand brakes (made by Tektro) for only $30 for a complete front and rear set. They are decent double pivots and you can't get an individual brake for much less.

I will assume your talking disc brakes here.
They both function the same, the real difference is the mounting. If you select front, the caliper will come with the mounting hardware for a fork. ANd come with mounting hardware for a frame if you select rear. Besides that, no difference i know of

Hummm. I assumed rim brakes so I wonder which it is. "Caliper" could mean either.

You can only find rears because everyone's using front calipers on their fixies. Get the rear caliper and use one of these longer nuts to reach the caliper's short mounting bolt through the fork crown:

(sorry, no canned photo today)


Also, make sure you reverse the pads if they're inserts. You don't want them sliding out when you grab your brake....

Well if you assumed rim, and i assumed disc. Then i think between that, the guys gotten the answer he needed.

I assumed rim brakes too. But no Nashbar for jur, due to his location.

yeah, my bad, meant rim brakes. Thanks!

Perhaps we should start a Nashbar branch here in Oz. Get some competition going.

Nope. There are a handful of distributors that own the market here. Now, someone in the US with some contacts...

I know that for the Avid SL rim brakes, the difference between front and rear is in the brake pads alone. The replaceable pads are locked in different directions, so that they're always pushed into their slots when you brake. The rear brake's pads are pushed in the opposite direction of the front ones. If you, like me, use different brake pads from the start, then they're identical.
I don't know, but I assume, this is true for most or all rim brake types.

I have used rears in the front for fixed conversions. I just use a bolt sleeve extender. No problems here.

Hillrider was right about the longer bolt on the front brake. However, changing the bolt isn't that big of an issue. When I needed to do it, just ordered the parts kit from Shimano (local LBS put the order in). It took maybe 15-20 minutes to change the bolt, and I'd never done it before.

My 2004 Trek 1000 and LeMond Big Sky has 2 brake sizes......long reach (57mm) on the rear and short (49mm) front.