CoOlSlY

I have an e-bike, my rear brakes are squealing from day 1. I tried the disc brake cleaner, tried to realign the caliper, tried everything until I decided to change everything. I ordered Tektro pads and Tektro disc and made the change. I went to bed the brakes and as soon as I applied braking for the first time, the same exact squeal was there. If i'm not braking, everything's fine.

I'm really out of idea of what it could be :| It's an NCM Moscow Plus 29" e-bike. Could it be the hydraulic brake cable? The hydraulic brake itself or even the fluid? I really have no clue and I went to a local shop and said "If you changed your pads and rotors, that's what we would do" so not really helpful. Hopefully some advices here will make my squeal stop (other than suggesting to change bike lol)

Iride01 

Maybe you are actively working too hard to try and do something and you are interfering with stuff that needs to happen pretty much on it's own.

So if you've made certain everything is installed properly by the manuals for those parts and cleaned properly then just give it time. Firm braking is good. But don't be ridiculous about it. And don't ride the brakes all the way to a stop from a high speed and get them overheated.

CoOlSlY

While I do agree to give them time, my first rotor and pads were squealing when new. I've put a few hundred km's on them and decided to change them so I don't know what could cause the squealing

montevista

Here's a long-shot suggestion from a very amateur mechanic, but perhaps double check that both the rotor and caliper are tightened to spec to the hub and frame, respectively. If loose, they may vibrate. I don't know if that vibration would make a squealing noise, but maybe it would cause some sort of stick-slip squealing between the pads and rotors.

CoOlSlY

You might not be wrong. The disc, if i tap on it, I can hear a vibration which is not present in the front. The screws are thight though, i'm trying to find a way to mitigate the sound of it because I want to sell the bike and get a new one so having that loud squeal everytime you brake is not a very good selling point lol

daverup 

If you have a leak in the brake caliper, a small amount of fluid will quickly start them squealing.