funny noise when braking

apple eater

My carrera has cable disc brakes.

Something has just started to happen when i brake. It makes a funny rumbly bearing type of noise. I've checked the bearings and all is fine, the wheel runs true. The disc isn't noticably warped and there is plenty of life in the pads.

Any ideas?

twonks

Some brakes just make a noise. Does it do it more noticeably when braking hard after a fast run?

My old Hope C2 brakes used to sound like a helicopter landing when braking from high speed

cycleclinic

Is the disc centered between the pads. If not the disc could be flexing when braking causing vibration and noise.

oxocube1

When ever i get a bike in with this sort of problem i just eliminate things one at a time.

1. Try resetting/re-aligning the caliper to make sure it is not rotor and pad rub.
2. Take the wheel out and use some disc brake cleaner and a clean rag on the rotor to get rid of any dirt/oil.
3. Take the pads out of the caliper and run some wet and dry paper over them to remove dirt or loose pad material.
4. If none of those work, try replacing the cable and doing all of the above.

Usually if I clean the rotor, I wet and dry the pads at the same time just to eliminate both possible causes at once. It may be worth getting a hub service done anyway. Just because there is no play does not mean there is no problem with the hub. The cones could have 'over tightened' which would certainly cause a rumbly/grinding noise because the bearings are being crushed against the hub recess.

They are usually Tektro cable disc brakes that come on the lower specced Carreras and there are certainly worse ones out there so they should not really be making the noise, especially if they have not been doing so the whole time.

Giraffoto

I used to have Avid BB5 cable-operated disk brakes, and they always made a squealing/grinding/rumbling noise under prolonged heavy braking. My first thought was that the pads were falling to pieces, but it just seems to be the noise they made. Do check that your pads aren't falling to pieces, though

Plyphon

I had a similar issue after washing my bike once.

The rear would sort of grumble, and you could feel the brake power almost pulsating as it grumbled away. Really off putting as it knocked my confidence when flying down fast sections knowing my brake wasn't working the best it could.

I tried everything under the sun short of bleeding the brake (as that 100% wasn't the issue) - managed to get a bit of power back. Still not perfect tho.

In the end I just went to DiscoBrakes and ordered a replacement pad for like a fiver.... came super quick and eliminated the issue. Brake working great now.

I think I was just unlucky when I washed the bike and some oil or grease perhaps splashed onto the rotor. Only thing I can think of.

spursn17

Brake cleaner in an aerosol can from the car spares shop is your best bet for cleaning brake discs/pads, just don't get it on your tyres as it distorts them.

leaflite

thecycleclinic wrote:

Is the disc centered between the pads. If not the disc could be flexing when braking causing vibration and noise.

IIRC, with cable disks the one pad should be virtually touching the rotor all the time as only 1 pad moves

YeehaaMcgee

spursn17 wrote:

Brake cleaner in an aerosol can from the car spares shop is your best bet for cleaning brake discs/pads, just don't get it on your tyres as it distorts them.

Nope. Isopropyl alcohol.
Some motor vehichle brake cleaners are way too harsh. I've had some just totally disintegrate the brake pad material.

Giraffoto

leaflite wrote:

IIRC, with cable disks the one pad should be virtually touching the rotor all the time as only 1 pad moves

You recall correctly for some of them: Avid BB5s (the only one of which I have any knowledge) have a fixed inboard pad which the disk runs closer to. Applying the brake pushes the outboard pad inwards and subtly flexes the disc, giving you a secure grip. What's the make and model of the brake that the OP's asking about?