and it is driving me nuts. The bike is new and the parts are all new, but after “fixing” this by loosening(sp) the rear brake pads and making sure the wheel is true, after riding for a 1/2 hr and checking, sure enough the wheel is rubbing on the pad. No broken spokes either. Someone mentioned the brake caliper may be set too tight. How do I know if it is set too tight? What is going on?
Is the pad rubbing the rim or the tire? If it is rubbing the tire?
Don’t ride until it is fixed if it the tire because you will burn a hole on the tire and flat.
A
If the wheel is true and the brake calipers are centered correctly, then the brakes shouldn’t go out of alignment so quickly. Do you have internal cable routing for your rear brake? If so, do you have enough ‘slack’ brake cable between the exit from the frame and the barrel adjuster on the caliper? If the length of cable between the frame and adjuster is very tight, it sounds like it could be pulling the brake over to one side causing the pad to contact the rim. Try putting a zip tie around the cable outer where it exits the frame to stop it pulling through inside each time you apply the brake.
If you don’t have internal routing, check that the the locknut (the barrel nut inside the chainstay bridge, normally a 5mm hex) is tight enough to stop the brake going out of alignment.