Just sorting out a Cotic X build, which I’m going to put Avid BB7s on. The X only takes a 140mm rear disc according to the website, and the BB7s come with a 160mm disc. Will the 160mm disc fit the rear, or must I get a 140mm? Will I also need a caliper mounting adaptor to fit the caliper to a 140mm diameter? Any idea which one I’ll need to order?

Cheers.

If it is a roundagon rotor just bin it and get a better one.

well, if cotic are saying it only takes a 140mm rotor, i guess it will only take a 140mm rotor. You need a 140mm rotor and a mount for the caliper to suit a 160mm IS front mount (an IS front mount also fits the rear -20mm on disc size).

luckily for you someone is selling a 140mm rotor and suitable caliper mount on the classifieds for much cheapness I seem to remember – have a look over the last couple of pages!

[EDIT]

in fact, here you go:-

http://www.singletrackworld.com/forum/topic/fs-avid-g3-140mm-rotor-with-adaptor

Its needs a 140. I have an X and there is little space for any else.

I did find on both ends that a wavy disc did not feel as nice as a round smooth one. I put this down to the way a cable disc works, ie one pad staying still and the disc being pushed towards it. Quite possibly others may not feel the same way but replacing the discs with round ones with less in the way of cut outs solved the problem for me.

Cheers all, I’ve found a cheapish source of 140mm discs, so I’ll get one of those. Do the BB7s need slick cables (gore type), or are they pretty insensitive to crud? Its been a while since I’ve had to worry about brake cables.

I used to run mine with just bog standard brake cables – full run front-back. They worked fine.