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Eliminating disc brake squealing

This post gives you step-by-step instructions for eliminating disc brake squealing during braking. A separate post explains how to eliminate disc brake rub – during riding, with brakes released. If rubbing problem is present, do read that post first. Why? Following instructions given there, ensures that brakes are functioning properly and the calipers are aligned with the disc. That could eliminate squealing as well. If it doesn’t help, or there is no brake rubbing, read on.

1. Organic vs sintered brake pads

Short digression (click here to skip it)

Main division of brake pad types is “organic” and “sintered”.

Organic brake pads (also called “resin”, or “semi-metallic”) are made of softer materials (kevlar, carbon, rubber with a minimum of softer metal particles).

Shimano organic ("resin") brake pads
Shimano organic (“resin”) brake pads
Picture 1

Sintered brake pads (also referred to as “metal”, or “metallic”) are made of metallic particles (glued together using high pressure and temperature).

Shimano sintered ("metal") brake pads
Shimano sintered (“metal”) brake pads
Picture 2

Differences of organic compared to sintered brake pads:

  • They are softer, so they wear discs less.
  • Generally less noisy when braking.
  • A bit better braking when cold (“they bite right away”).
  • They overheat more quickly and brake worse when hot.
  • Worse performance in wet and muddy conditions.

End of digression

Why is this important? Some brake discs are designed for organic brake pads and if used with sintered pads they will make unpleasant noise. The only solution in this case is swapping either pads, or discs – so they are “matched”.

Brake disc designed for organic ("resin") brake pads exclusively
Brake disc designed for organic (“resin”) brake pads exclusively
Picture 3

Not all the models of all the disc (and brake pad) manufacturers are so nicely labelled. In that case, look up manufacturer’s instructions/manuals (for both disc and pads, to see if they are “matched”). If there’s no manual available, last resort would be getting a two new pairs of pads: organic and sintered, mounting them (make sure the disc is cleaned, as will be explained in chapter 2) and seeing if one of them works fine.

2. Cleaning and degreasing

Dirty and greasy pads and discs are known to squeal when braking. How to clean them?

You will need:

  • A cloth for which you are certain it isn’t dirty, nor greasy/oiled.
  • Disc brake cleaner (available in auto shops), or alcohol with over 90% concentration (available in supermarkets). Both are FLAMMABLE, work in a well ventilated area, away from sources of flame, or heat.
  • Sandpaper with grit around 80.

It is basically the same whether you use alcohol, or disc brake leaner. I’d say disc brake cleaner does the job a bit quicker (perhaps better), but can damage plastic, rubber, or paint (depending on cleaner model) so be careful. In the remainder of the text I’ll be using the term “alcohol” – it is shorter (you can use whatever you like).

  • Remove brake pads. Clean brake calipers with a cloth, to remove any dirt, or brake fluid.
  • Clean the pads using a (clean) cloth and alcohol.
  • Place sandpaper on a flat surface (or a sandpaper holder) and rub the pads flat over it – to remove a thin layer of brake pad surface (don’t sand them down until they are worn, just remove the outer layer).
  • Clean the pads again using cloth and alcohol.
  • Clean brake discs using a cloth and alcohol. Clean them thoroughly. Dirty disc can contaminate the pads (and vice versa).
Sintered brake pads before (right) and after sanding (left).
Sintered brake pads before (right) and after sanding (left).
Source:, member WR304
Picture 5


If pads have been contaminated with an amount of grease/oil that is not extremely small, they will suck it in (brake pad material is porous). In that case, no amount of sanding and cleaning will help. Some suggest to “burn” such pads in an oven, or on a stove. High temperature could burn the grease, but could also cause the pads to start to slowly lift off the metal that holds them in place (not always visibly). I wouldn’t risk this with brakes – get new pads… or don’t – it’s your bike, money and life.

Amazon affiliate links:

Disc brake cleaner - click to shop
Disc brake cleaner – click to shop
99% alcohol for cleaning - click to shop
99% alcohol for cleaning – click to shop
Microfiber cleaning cloths - click to shop
Microfiber cleaning cloths – click to shop

The existing comments posted under this article (questions and answers) have been moved to this BikeGremlin forum thread:

10 thoughts on “Eliminating disc brake squealing”

  1. Hi Relja just a tip for those older aero retro levers you set them up for braking down in the drops,you put them down lower than the newer ones which you brake from the top,and the aero levers are better suited for the older round drop bars,the newer drop bars are shaped different,i also made a retro style bar tape out of old bicycle tube,it looks exactly like the retro cloth bar tape,best bar tape i have used yet,i spliced the tube in two strips with a pair of scizzors and wrapped the tube quiet tight and held it in place with electrical tape,now it matches my home made hoods,new tape does not suit an old retro build,i just picked up and old retro gemini racer all high end tubing and made for speed,what did surprize me was how light the bike actually is and how well made it is,just finished a total rebuild with modern wheels and components,everything fitted fine,most retro racers all had sticky cloth tape on them or real leather ones,this gemini looks like its from the 1980 period as it only has a five speed downtube shifter,what is also interesting what i dont see very often on retro bikes, is it has rear axle adjusters on it,still has the cromoly sticker on it but it could be from any tube maker as many tube makers back then did do cromoly but rebranded that tubing to suit their company,its such a pleasure to work on a nice retro bike but its getting very hard to find a nice one that has no bad damage,its a hit and miss with these older ones,you might manage to find one good one out of every five you find,i was lucky with this one as my friend had looked after it and he just donated it to me cheers,give me steel any day

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