Adjusting disc brakes is pretty straightforward. What you’ll need is a rubber band and an allen wrench.
Yep. That’s it.
To start, you’ll have to slightly loosen the mount bolts that attach the caliper to the adaptor. Once done, put the rubber band on the brake lever, causing it to close. This will align the caliper over the disc.
This is where you can fiddle around and tighten a tad so that you get the adjustment right. Once you’ve got that, you can take the rubber band off to hear how the wheel spins. If you still need to adjust, fine tune via the mounting bolts. Check and see if the distance between the disc and the both brake pads are even.
Tighten and you’re done!
In order to straighten lightly bent disc brakes, you are going to need one of two tools: a disc brake rotor tool or (if you don’t want to shell out the coin for this specialty tool) an adjustable wrench will do you nicely. Make sure it doesn’t have teeth and is flat so that it won’t leave marks on your rotor.
Once you’ve found the bent bit, use the tool of your choice to straighten. Once you’ve gotten it more or less straightened and the disc isn’t rubbing against any surface, you are pretty much good to go.