Avid BB5 asymmetrical pad rub position and squeal
Having seen some mechanical disk brakes over my life, the Avid's 9 out 10 will emit some sort of sound.

You indeed are correct about how a mechanical disk brake works, by bending the rotor. So it's most important to set them properly. This is my procedure:


Take the caliper off, and check that the pads are parallel. Clean them if necessary.
Check if the rotor is tightly bolted to the hub.
Set the fine adjustment bolt on the lever and the caliper to none(all the way in)
Mount the caliper and bolt only using your hands
Bolt the cable lines.
Set, the static usually, adjustment to lock the rotor, then set it back half a turn.
Now, hold the handle with a ziptie and lock the brake.
Meanwhile use a hex tool to tight the caliper bolts
Finally, fine adjust the brake line.


Hope this will help you.