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I have a commuter bike with Tektro MD-285 hydraulic disc brakes. I commute about 14 miles every day (7 in, 7 out) in most types of weather, but I am not a performance cyclist by any means. It's just a good way to get to work. For the past few months, I have had a bit of a squeal and a shuddering noise that I can feel through the handlebars on the front brake when I brake it hard. When slower there is really little to no noise. I cannot for the life of me figure out what is going on. Here is what I have tried:

  • Sanding down and cleaning new pads and rotor.
  • Getting new pads and rotor and going through the bed-in process.
  • After replacing, pushing the pistons back in on the brake to try to ensure they are parallel and the whole pad is hitting the rotor.
  • Made sure the headset was not too loose.
  • Checked the AL fork for any cracks.

Any other ideas? Worth bleeding the brakes?

  • From my limited experience of hydraulics this isn't the sort of thing bleeding helps with. Is everything tight? Is there any weather dependence? Is the new rotor the same as the old one (the Shimano rotor on my dynamo wheel causes a little vibration while the promax on my original wheel doesn't; cable discs on that bike)? When I get a more musical sound (either bike with discs) it's normally a bit of grit in the caliper housing. – Chris H Jan 23 at 22:25
  • There is no weather dependence; it is the same rain or shine, and in warm or cold weather. Everything seems to be tight too and the calipers seem centered. The replacement is a Tektro rotor with the same hole pattern and also Tektro pads. The brake does not feel soft, so I wouldn't think bleeding would work, but I'm at a loss. Could there be gunk on the pistons preventing one from coming out flat with the rotor? The noise almost sounds like a corner or edge of the brake pad hitting the holes of the rotor. – Jared R. Jan 24 at 0:57
  • Check your front wheel for loose spokes and cracks in the rim, especially around all the spoke holes. – Andrew Henle Jan 24 at 11:26
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    Do you have a friend with a wheel that you can fit in your bike? If you find that using a different wheel and rotor fixes the issue, then you know where your issue is. If it doesn't, then you've at least ruled those two things out. – Carbon side up Jan 24 at 11:45
  • Those are both great suggestions. I forgot to mention that I recently bought a new wheel because the bearings were rusted out, and the hub is supposed to be "non-servicable". The hub is a sanyo/panasonic dynohub, but with a 6-bolt disc attachment, and I couldn't buy the hub by itself anywhere. The problem exists with both wheels, and even after putting a new rotor on the new wheel. It seems like the only thing left is the caliper, no? – Jared R. Jan 24 at 13:54
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Replaced the brake and all is well. My guess is one side of a piston was being pushed out with more force than another.

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