Bicycle Mechanics - Cantilever Brakes off center - Very frustrating

First of all, I'd like to say I did my homework on this one. I checked the Park Tool site, Sheldon Brown, and some others. Basically what's happening is that one side of the brakes is hitting the rim before the other. Even if I have the pads perfectly centered, when I pull the side where you release them is moving before the side where the anchor bolt is. I've tried adjusting the transverse and cable that comes from the brake lever. I've tried centering them with the allen key on one of the cantilevers. I've run out of ideas.

One thing I do see is that after I squeeze the levers, the carrier seems to move off to one side. It doesn't seem perfectly centered. How can I change that?

Is the gap between the rim and the fork blades (or rear stays) exactly the same on both sides? It could be your rim is off center from the frame.

Is the gap between the rim and the fork blades (or rear stays) exactly the same on both sides? It could be your rim is off center from the frame.

Huh? Offcenter from the fork yeah?

First clean and grease the pivots. Switch the return spring on one side to the next hole at the base of the boss. Then readjust the centring screw.

If you've ever overtightened the bolts, you could have mushroomed one of the canti studs, creating friction.

Thanks for all the help guys. Yes, my rim and wheel are centered. That was the first thing I checked. I do notice that if I adjust the centering by using the allen key I can get them to line up pretty well, but when I squeeze the brake levers they seem to go back to their slightly un-centered alignment. I think I'll clean them up a little and loosen the bolts a little and see what happens.

I've had this problem too and it seems to be caused by either unequal spring tension (one side is tighter than the other) or friction.

Having the brakes centered with the lever released isn't too big an issue. As long as the pads aren't rubbing on the rim you're fine.

What you don't want to have is the brakes clamping the wheel unevenly which pushes the rim to one side or the other when you're squeezing the brake lever.