Hello, I recently bought a pair of Avid BB7 mechanical disc brakes. I'm positive i have them set up correctly and the back brake works perfectly. The front brake seems to have almost no effect at all. I bought these about 2 weeks ago and have ridden the bike pretty much every other day. I really hope sanding the rotor wasn't damaging it because me and my dad thought it would help roughen it up and little and make the pads grab better.