Squealing disk brakes
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Discussion

Dr Murdoch

Original Poster:

3,943 posts

164 months

Monday 5th June 2017
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Hi

Ive got a new bike, but the brakes are driving me mad! I've done about 75 miles but the brakes are still squeaking.

Should I be patient and give them more time?

Looking on google, some are suggesting sanding the disks with sand paper, really? Seems a bit much.

CharlieCrocodile

1,227 posts

182 months

Monday 5th June 2017
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Take it back. I've just done 350+ miles in 2 weeks on a new bike with discs without any noise whatsoever.

TwilightJohnny

537 posts

239 months

Monday 5th June 2017
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Is it a constant squeal from the pad rubbing on the disc or just when applying the brakes?

If the former undo the two caliper mounting bolts with a 5mm allen key and recentre the caliper so the disc runs freely between the pads. It can take a bit of patience as the caliper will move as you tighten the bolts but spin the wheel and tighten slowly and you'll get there.

If it's when applying the brakes you can clean the disc with brake cleaner or just soapy water and see if it improved things. It may not. If not take out the pads and give them a clean too with soapy water, resurface with a file or emery paper and see if that helps. If not the pads are probably contaminated with something and may never improve. New pads are cheap enough but as said above, take it back to the shop and get them to sort it. New brakes shouldn't squeal.

greenamex2

509 posts

284 months

Tuesday 6th June 2017
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Does it just happen in damp conditions (rain/mist)?

Gren

2,030 posts

281 months

Tuesday 6th June 2017
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Never had a disc brake that doesn't squeal in the wet - road or mtb. Sram, Shimano or Formula.

Dr Murdoch

Original Poster:

3,943 posts

164 months

Tuesday 6th June 2017
quotequote all
Thanks chaps

Haven't ridden it in the wet yet, so I only know that they squeak in the dry.

Its due to go back to the shop in 2/3 weeks to get the cables adjusted after the bedding in period. I will mention the brakes then and ask them to fix them.

Agent XXX

1,248 posts

135 months

Tuesday 6th June 2017
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Squirt some GT 85 or WD40 on 'em. That should stop 'em squealing.
wobble

Gary29

5,192 posts

128 months

Tuesday 6th June 2017
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All disc brakes I've used (Cable and Hydro, MTB and Road) have all squeaked to some extent, they are very sensitive to changes in humidity and temperature and foreign matter on the disc surface.

I'm guessing the bike shop won't be abel to 'fix them' in any way whatsoever further than throwing a rag covered in brake cleaner over them.

Mine tend to be worse at the beginning of a ride and even worse in cold conditions.

donfisher

793 posts

195 months

Tuesday 6th June 2017
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In the past I found sintered pads to be horrendously, embarrassingly noisy.

Switching to semi-metallic fixed this, they’re now almost silent apart from a very slight chirp the first time they get used in the wet.

The wear rate is not too reduced either. Maybe they actually get used more efficiently as they’re not getting feathered to avoid that awful screeching.

boyse7en

8,167 posts

194 months

Tuesday 6th June 2017
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I had some Shimano discs that squealed horrifically - they scared small children in the dry and in the wet they were like an air-raid warning. People 100yds away would look up.

I tried cleaning the disks, adjusting the caliper and changed the pads twice in an attempt to cure it.
In the end I bought a set of Deore discs, calipers and levers and replaced the lot. Been fine since.

Johno

8,593 posts

311 months

Tuesday 6th June 2017
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Metal pads are the worst, especially after rain.

Resin pads are much better, but not immune.

Once they're really bad and without a long descent to clean themselves off then I do wet and dry the discs and pads to remove the glaze that forms, cleaning off reissue with Burke cleaner. Some times a bit of brake cleaner will do it alone, but a proper deglaze with fine wet and dry is best. Do the braking surface only and for the pads put the wet and dry on a flat surface and lightly run the pad over it to try and ensure it remains a uniform flat finish.

Also when new, pads and discs do need bedding in, a quick step through that is wet and dry, but the other is to use me really hard if possible, big hills being preferable to repeated full out sprints and emergency stops!

IREvans

1,126 posts

151 months

Wednesday 7th June 2017
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Dr Murdoch said:
Hi

Ive got a new bike, but the brakes are driving me mad! I've done about 75 miles but the brakes are still squeaking.

Should I be patient and give them more time?

Looking on google, some are suggesting sanding the disks with sand paper, really? Seems a bit much.
I have a disk braked road bike, with 160mm front and rear Hope floating discs, and Shimano hydraulic calipers. I have used both the sintered metal, and resin pads. Sintered last longer and give greater stopping power. But importantly, they never squeal.

They do take some setting up - As others have mentioned, you need to first push the pistons back into the calipers, then fit a pad spacer (which should have come with the bike/brake kit), and operate the brakes to set the pistons in the correct positions. Then you need to loosen the caliper on the frame, refit the wheel onto the bike, operate the brake lever, then tighten the caliper bolts. That should be it.

They can sometimes squeal a little until the pads are bedded in, but a few big stops should bed the pads