Squealing rear disc

Discussion in 'Bicycle Mechanics and Repairs' started by Yellow Fang, 7 Mar 2008.

  1. Yellow Fang

    Yellow Fang Guru

    Sorry to post on such a mundane topic, but does anyone know the likely cause and what to do about it?
  2. bonj2

    bonj2 Guest

    squeeling or grating?
    if grating/grinding noise, (like not high pitched) - then, are they avids? If so, I had the same problem, and cured it by upgrading to formulas.
  3. Jacomus-rides-Gen

    Jacomus-rides-Gen New Member

    Guildford / London
    Can be anything, do you want to be more specific?

    can be wet
    glazed pads
    loose pads
    loose rotor
    something on the rotor
  4. OP
    Yellow Fang

    Yellow Fang Guru

    It's squealing, and they are Hope discs. They're not wet or greasy. I'm pretty sure it's not something on the rotor. What does 'blued' mean? I'll have to check the pads and rotor.
  5. Tynan

    Tynan Veteran

    my last bike had discs and they tended to get a noise that sounded like grit grinding when I applied the brake

    which is what it was, LBS said it was a matter of running the wheel backwards while gently applying the brake

    still think it was shitty design if so
  6. Tim Bennet.

    Tim Bennet. Entirely Average Member

    S of Kendal
    Are they Hope mini's?

    Things to check:
    1. That the rotor bolts are tight.
    2. That the caliper mounting bolts are tight.
    3. Take the pads out and rub their braking surface on some clean, dry fine sand paper. Then clean the metal backs of the pads and apply a thin smear of grease or Neverseeze to the surface of the metal.
    4. Clean the rotor with meths.
    5. Take bike to top of a steep road hill (Kirkstone) together with a bike bottle of clean water. Give the pads a good soaking with water and set off down the hill applying the brakes as much as possible. Every 30 secs, stop and put more water on the brakes. This is the fastest way of getting the pads and disks to 'mate' together.

    Bluing is where the disk has over heated and a slight 'blue' tinge can be seen on the rotor.

    I had a disk that I couldn't stop sqealing on the front of my old Whyte mountainbike until I had the mounts 'faced' by the LBS. But all disks seem to have their squealy moments and as long as the mounting bolts are all tight and the pad free to move slightly in the calipers (crud free with a lightly greased back plates), then sometimes it's just easier to 'ride through it' till it sorts itself out.
  7. Monst

    Monst New Member

    The boonies
    contamination on the disc - most likely slight overspray from oil or bike cleaner etc.

    Buy some bike specific disc brake cleaner.

    It works - my bike squealed like stuck pigs, until I cleaned them. Seems the car shampoo I used to clean the bike left a slight residue on the disc - thus brakes squealed. Used a bike disc specific cleaner like muc off disc brake cleaner and now all is well...
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