Why do disk brakes squeal?

[Luegolover]

So I have riden lots of motorbikes over the years and not once have I have a bike that has brakes that squeal so I am somewhat put out by the noise that my disc brakes make on my new road bike. Is there a reason for brakes squealing that I don't realise? Do I need a certain type of disc pads? Have I got dodgy rotors?

Pads: not sure what brand but I may have the packaging somewhere so I could possibly find out.
Rotors: Avid, stainless steel.
Callipers: Hope

Any suggestions?

 

[PK99]

Chapter and verse......

http://www.pinkbike.com/news/Tech-Tuesday-Silence-That-Squeaky-Disc-Brake-2011.html

 

[Cubist]

Disc brakes squeal for a whole host of reasons. Contaminated pads, mis-aligned calipers, contaminated rotors, new pads, new rotors, the list is lengthy. Try and bed them in by riding down a steep hill, braking to the point of stopping several times so that they get really hot. Squirt cold clean water over the pads and calipers from a bidon and with any luck you'll hear a hissing noise. Check that they are properly aligned and adjusted. I presume they are mechanical on a road bike rather than hydraulic?

 

[Luegolover]

Thank you very much. If it works it will be thank you very very very very very very very much.

 

[Luegolover]

They are the Hope hydraulic V-twin set up, so the calliper is hydraulic. They work ok, just make a load of noise. The pads are new but the rotors are second-hand but in good condition. I will do the stuff suggested on the pink bike site and see what happens.

 

[Globalti]

If they squawk and judder just as the bike rolls to a stop, they are contaminated with oil. Clean discs with glass cleaner and put the pads in the dishwasher.

 

[Klassikbike]

I thought that squals from Avids are normal

 

[mrbikerboy73]

If they squawk and judder just as the bike rolls to a stop, they are contaminated with oil. Clean discs with glass cleaner and put the pads in the dishwasher.

Surely glass cleaner is for erm....glass? Why not use proper brake cleaner instead?

 

[Globalti]

Because most people have glass cleaner in the cupboard and it works pretty well.

 

[0lonerider]

isopropel spirit (c.d cleaning fluid) works best as it leaves no residue.

 

[Nigeyy]

Wouldn't you if you had pinched discs?

 

[Luegolover]

Well I cleaned the pads and the discs thoroughly and now the squeak has gone, thank heavens. Thanks for the advice.