Bedding brakes?

[djg21]

Looks like I screwed up. I never bedded the disc brakes on my new gravel bike because I didn’t have any experience with disc brakes previously and didn’t know it was necessary. I probably have a couple hundred miles on the bike now. Is it too late. If I clean the pads and discs with denatured alcohol can I try to go through the process now? How can I eliminate brake squeal. It only happens infrequently, usually when I’ve had to brake firmly during a downhill.

[Hilltopperny]

I am not sure if you can avoid the dreaded brake squeal of disc brakes. The pads will typically bed when riding it the first couple of times, but when the disc gets wet or contaminated it will likely squeal as mine did when we rode a couple of weeks ago!

The bedding process is more for ensuring the brakes stop well.


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[fmradio516]

I never have problems with my disc brakes squeeling on my mountain bike and i ride through streams with it.

Sand down the pads and rotors a wee bit, clean up with alcohol and then bed in the brakes as normal.

[grumpus]

First disclaimer, disc squeal can come from tons of different things, so a 100% perfect bed in procedure may not fix the problem.

My understanding of the bed in process is that your goal is to deposit a coating of brake pad material onto the disc. If you start with a brand new disc and brand new pad, you don't get optimal friction between the surfaces. Especially in combination with high speed/pressure braking, this will spike temperatures, increasing the likelihood of your pads glazing. Glazed pad provides less friction and can lead to squealing. Glazed pads also won't deposit pad material as efficiently onto the disc, so the bedding in process won't progress on its own.

This is why the bed in procedures will call for a gradual increase in braking pressure. You want to transfer pad material do the disc while staying under the glazing threshold. Once enough of the pad material is built up on the disc, you get optimal friction, and your pads are much less likely to glaze.

If I feel that my pads have glazed, I usually hit the pads and rotors with a light once over of 220 or 400 grit sandpaper, a thorough cleaning with a solvent, and then a thorough bed in procedure. I think the sandpaper is necessary to cut through the glaze. I have noticed an improvement after doing this procedure. I may be wrong about all of the above and the improvement may be placebo.

[eddief]

and sand them down until you get the top layer of what's on them off, then clean the rotors will alcohol, then re-insert pads, and then do the bedding process it will work fine.

[joevers]

Originally Posted by fmradio516

Sand down the pads and rotors a wee bit, clean up with alcohol and then bed in the brakes as normal.

This. Nothing special. If you pull your pads you'll probably notice they're glossy. Sand them until they're not glossy, clean the rotor with alcohol then go bed them in and you're good.