Symptoms
- High-pitched squeal when braking
- Squeaking happens even with light braking
- Noise is worse in wet weather
- Brake pads look shiny or glazed
Likely causes
- CommonContaminated brake pads (oil, grease, or road grime)Contamination changes the friction surface and causes noise and reduced stopping power.
- CommonGlazed brake padsOverheating from long descents or old pads can harden and glaze the surface.
- CommonMisaligned brake padsPads that don't hit the rim or rotor evenly and flat often squeal.
- PossibleDirty rim or rotor surfaceRoad grime on the braking surface itself can cause noise.
What to do
- Clean the rim (for rim brakes) or rotor (for disc brakes) with isopropyl alcohol and a clean rag.
- Inspect brake pads for contamination, glazing, or uneven wear.
- Lightly sand glazed pad surfaces with fine sandpaper to restore some grip, or replace pads if heavily worn.
- Check rim brake pad alignment so pads contact the rim flat and don't touch the tire.
- For disc brakes, check the caliper is centered over the rotor and not rubbing on one side.
- Reinstall and test brake feel and noise on a short, slow ride before going further.
- If squeaking continues after cleaning and alignment, new pads and possibly a new rotor or rim cleaning may be needed.
Tools and parts
- Isopropyl alcohol
- Clean rags
- Allen key set
- Fine sandpaper
Bike brake padsSearch: “bicycle brake pads replacement”
When to call a pro
A bike shop can true a warped rotor or rim and align brake calipers precisely if cleaning and pad replacement don't stop the squeal.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.