Originally Posted by
5b00
I believe that I have the same combination of rotor (SM-RT78 from Nashbar) and brake (Avid BB7 road). I also had problems with weak, pulsating brakes. If you look closely, the brake track on the XT rotor is narrower than is typical. This means that your pads are probably hitting the arms, which causes the pulsing sound.
Give that man a cigar. Yes, the XT brake surface is different than the Avid, so much so that given certain configurations the brakes are actualy hitting the center web of the rotor.
And sanding them was certainly not a good idea. Rotors are blanchard ground to assure a consistent surface finish.