Hi, fellas,
I’m in love with my new ‘26 Cube Reaction TM Pro. Flawless bike, except this occasional disc grinding noise since day 1. The weird thing is that it occurs randomly, sometimes goes away for a few kms, then it appears back again. I press the brake – it’s there, I press again – it’s gone and back again in a second, or a minute. There is no exact reason, it continues even after pad replacement (resin ones from Cooma), bike shower or disc cleaning. Wet or dry weather, same
thing. It’s not related to the piston either – the pistons move back every time when I release the lever.
Any ideas?
Front brake disc grinding – Shimano MT520
byu/f9lix inbikewrench
by f9lix
5 Comments
So many things that could be wrong. We would need more pictures and videos with light.
I would first check your pads, that sounds more like metal on metal and could be a sign that you don’t have any compound on your pads left.
If you have pads, check that your caliper and rotor are aligned properly and bolted down snug. Same with your rotor
Disk is not aligned to the middel of the brake caliper,it touches the housing of the brake caliper
Braking will cause rotors to heat up. Cheap plain rotors are more likely to warp when heated up. Quality floating rotors are less likely to warp. Warped rotors rub the pads.
Metalic pads are the noisiest. Resin pads are the quietest.
Improperly aligned calipers will cause more pad/rotor rub.
Do an idiot check first.
Simple things. Is the wheel properly mounted in the fork, are the brake disc and caliper bolts tight, is the return spring on the inside of the brake pads?
I say this as it sounds more like something is loose and rattling around than brake disc rub.
That does not sound like the disc is rubbing so much as it sounds like the caliber is loose.