Originally Posted by
jargo432
I'm having trouble getting my rear disc brake set up on my DT build. (I've got the front working perfectly) I've worked very hard getting the caliper straight. When I adjust the inside and outside to where there is no rub, the brakes are very weak. The rub is intermittent, which makes me think the disc is not straight. I'm thinking about removing the disc and testing it to see if it perfectly flat. (or maybe I didn't mount it right)
Has anyone else had a disc that wasn't true?
A better question would be has anyone else had a disc rotor that
was true. I've owned a lot of disc equipped bikes and never had a disc rotor that didn't need some adjustment. Rotors have to be much truer than bike wheels and they seldom are.
To true the rotor, leave the rotor on the wheel and keep it mounted on the bike. Sight down the gap between the pads in the caliper and see where the wobble is. You can use a
rotor tuning fork or even a large cresent wrench to gently bend the rotor to trueness. Make only small corrections at a time and constantly check the wobble against the calipers.