From Unofficial Zero Manual
This covers general problems with brake pads, in terms of typical symptoms.
- Brake Squeak
- Brake squeak (pad front against the disc) happens occasionally and is relatively quiet and noticeable but not anomalous.
- Brake Squeal
- Brake squeal (pad back resonating against caliper cylinder) can be very loud and annoying. Squeal does not technically impact performance but it's very unpleasant and might cause the rider to hesitate before fully braking which is a safety issue.
- Clean the pads and/or discs for squeaking.
- Try a different brake pad (attractive if you want a different pad feel or performance in the first place).
- LocTite Disc Brake Quiet stick applicator for the backs of the pads.
- Chamfer the brake pads
- File the edges of the pad to put a 45 degree edge on them
- You only need 1-2mm