Answered Help needed - rear brake squealing like a Foghorn and vibrating.

[R120]

So after about 20 miles into my maiden outing on my new E-Sentier hardtail this morning, and having though i had beded in the brakes on a quick ride last night, the rear brake started squealing badly, like a foghorn, and sending a lot of vibration through the bike. No idea why, and never had this problem before. Bike is an E-Sentier Hardtail, with Guide RE's. Any help appreciated as at this point i am thinking of just getting a new rotor.

 

[Gary]

TBF I only ever run 160mm discs on any hardtail.
Specing 200mm Guide REs on any hardtail seems massively overkill to me.

 

[R120]

Yes 180mm has solved the issue, along with not strangling the hose by doing the tie up too tight. Braking has actually improved as a result too, far more progressive on the rear now , was a bit on/off with the 200mm.

 

[Coastsider]

Seems you have this fixed now but I had the same issue but on the front disc with the Magura set up on my Moustache Race 8, howling monkey. Solution: clean disc with brake cleaner (use gloves) resurface disc and pads with 200 grit sandpaper on a flat surface, clean again with brake cleaner. Then here's the important part, the pads need to be bedded in properly so the surface of the disc gets a coating of pad material. 12 fast and hard repeated short braking applications to do this and my brakes were blissfully quiet again.

 

[R120]

Yeah i fully cleaned and resurface the disc and made no difference - the issue here is particular to this model of bike, and i think a design fault more than anything else - the noise isn't form the brakes, although it appears to be when it manifests itself - its actually the frame resonating.

 

[Rob Rides EMTB]

Hey @R120 can you mark which post you found to be the best answer? (click the trophy on left hand side next to username!)

 

[smokey_jo]

I'm not sure that noise is coming from the frame. My front Deore brake is currently making that exact same noise. I've pretty much nailed it down to pads getting contaminated at the caliper by a bad seal ( Deore are known for this). If you're caliper has a sticky piston that points to a badly fitting seal in the caliper which could weep fluid into the pads. If your noise returns that's what if look at next