ridethetown

I'm experiencing a "buzzing" sound from my front disc brake when braking. I don't feel it in the lever and it doesn't seem to be compromising my stopping power, but it's annoying as hell. It's a brand new Ultegra setup with the Ice Technologies rotors.

I cleaned the rotors with 70% IPA but no difference. I've read that it's normal with some rotors due to the hole pattern - is that right, and/or something anyone's experienced with the Ice Tech rotors? Doesn't seem like something you'd just have to live with..

Cyclist0108

I have ice tech rotors on several bikes and have never had this problem, so I don't think it is inherent to the rotor design.

Check the pads and caliper. Make sure they are installed properly and aligned. It might help to sand the pads if they look glazed.

With the pads taken out, turn the wheel and watch the rotor. It should turn without wobble with respect to the slot in the caliper.

Also check to make sure the bolts (or lockring) that hold the rotor to the hub are all tight to the torque spec.

hokiefyd 

Does it seem like the pitch of the buzz is related to speed? That is, the faster you go, the high-pitched the buzz? And the slower you go, the lower-pitched the buzz (or even completely quiet)? Every set of disc brakes I've personally owned has done this. The buzz on mine seems be loudest if just barely dragging the brakes. Get on them hard and the buzz either goes away or it's overcome by the sound of strong braking.

For what it's worth, my experience has been with MTB style disc brakes, both cable-operated and hydraulic. The two bikes I ride the most have hydraulic discs, with completely different styles of brake disc. Despite entirely different shapes and patterns of the holes, the buzz is pretty similar. The sound doesn't seem to be as loud with cable-operated discs. Is this because one pad engages before the other on these, but both clamp at the same time with hydraulic brakes? I couldn't say for sure.

fietsbob

pads only grabbing the edge, not the disc'spokes'?

dsaul

Look at the wear pattern on the disc and see if the pads are sweeping the arms of the disc. That is usually the cause of buzzing when braking. The caliper may need to be shimmed up to make sure the pads don't hit the arms of the rotor.

ridethetown

So I swapped my wheels from my gravel bike, which runs the same wheel set with the 105 level rotors and at first had no noise, but started noticing it on a big descent when braking at over 30 mph. Then I'd notice it when braking at speed for the rest of the ride, but less so than with the Ultegra Ice Tech's. Again, I was confident in the braking power despite the noise.
@dsaul - I think you may be on to something. I'll check that out.

hokiefyd 

I checked one of my bikes and it does appear that the pad sweep area does dip down just below the smaller diameter of the wear surface, and into where the arms are. What might one use to shim the caliper -- just a simple washer or two? Mine are post-mount calipers without the ball-and-socket alignment washers that some calipers have...so I suppose it'd be best to use an equal number of washers (1, 2, etc) on both sides between the post and the caliper.

dsaul

Shims would be preferable, because they are machined flat, but I would probably just try a washer under each side of the caliper. Definitely use an equal amount of shims/washers under each side.

bigredgrad01

I am having same issue, when braking at high speed. Changed the pads already.
Did you end up resolving it with shims?