there is usually a small allen key for centering the brakes on 1 side of the caliper, similar to v brakes, if not then you should beable to centre them by tightening them normally against the frame/fork then adjusting them by using a cone spanner (because it's thin) on the flat edge bolt between the brake and the frame, this is a centering nut, by simply moving it either way it should adjust the position of the brake giving you an even pad contact on the rim.
hope that makes sense, i'm a little pissed at the mo and the ex has been around to annoy me! so i could be wrong and probably am!!!
one day i'll be free of her!!!!!!
You have enemies? Good. That means you've stood up for something in your life.