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I just built a mountain bike with Avid BB7 brakes and Shimano V-brake levers. I used the exact same configuration on another bike, and it worked beautifully. But on this one, the brakes are just weak as hell. I know that disk brakes are supposed to have a short break-in period, but I'm way beyond that now, and still no change. What's going on and how can I fix it?

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Are they properly adjusted and mounted? What pads and rotors are being used? We need more details. – whatsisname May 12 '13 at 14:59
Make sure you purchased long-pull BB7 calipers and not the short-pull versions specific for road bikes! – WTHarper May 12 '13 at 16:00 ... You can see there are quite a few versions. – WTHarper May 12 '13 at 16:01
Yes, I have the long-pull MTB version. Rotors: 160 rear, 180 front. I'm using the pads that came with the brakes. – Mike Baranczak May 12 '13 at 16:14
how much time did you have to break them in? – trailmax May 13 '13 at 9:02

Avid recommends breaking those discs and pads in with about 30 or 40 deliberately hard stops in order to build up a good foundation. If you've gone through that process a couple of times and still no dice, there could be brake fluid on the discs or pads. Some water or isopropyl alcohol should take care of that.

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BB7s are mechanical discs. – WTHarper May 12 '13 at 21:09
Oh that's right, forget the part about bleeding. – hillsons May 12 '13 at 21:24

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