noisy disk brakes

[Cdalekat]

As far as I am aware, there are two probable causes. Cause one - dirt and oil. Cause two - misalignment and vibration.

For dirt and oil, start by cleaning your rotors with alcohol (and never touch them with your fingers least you get more oil on them). It may also require removing the pads and lightly sanding them with extremely fine grit sandpaper to break any visible sheen (and take off the layer of oil and dirt that's probably on them). There's always the option of completely replacing your pads too.

For misalignment and vibration, the bike simply needs to be checked out. Is everything functioning properly, are your wheels true, are the break pads the correct distance from the rotor, etc, etc.