I bought a new bike last week that has Tektro HD-R280 hydraulic disc brakes. I noticed on my first test ride that the front brake was rubbing against the rotor, but only when turning left. Since I found this very annoying, I tried to center the brake by loosening the caliper, pulling hard on the lever and then retightening it. This would fix the problem, but I noticed that after braking once or twice, it would start to rub again. I thought at first that I didn’t tighten the caliper enough, but after closer inspection I noticed that it only happened when braking softly. When I brake hard, the rubbing is gone. I noticed that when I brake softly, one of the pistons/pads doesn’t fully retract and the pad rubs on the rotor. When I pull the lever hard, it does retract, and the problem is gone. I don’t understand how this can happen, so I also don’t know how to fix this. The bike is brand new, so the seals should still be fine. If one of the pistons would have been pushed through the seal more while I was trying to adjust the brake, that could explain why it’s further out, but not that it retracts to its original position when I pull hard on the brake lever. I could take the bike back to the shop, but it’s a one-hour drive so if I could fix it easily myself, I would prefer to do that.
If the caliper was off center, the pistons may have extended unevenly during the initial use. Here's how I would address this:
- Remove the wheel
- With nitrile gloves or very clean hands: remove the pads
- Push the pistons all the way back into the caliper with a plastic tire lever or specialty tool
- reinstall pads
- reinstall wheel
- recenter the caliper again.