kosmo886

I feel like this happens on all my bikes...the front disc rubs as I ride. Does this mean the rotor is bent or is there an easy adjustment of some sort?

colnago62

Bent is too strong of word. It is probably tweaked. It is an easy fix, get the right tool though.

kosmo886

What is the right tool?

colnago62

A rotor trueing tool.

WhyFi

Does it rub all of the time? Or only in wet weather or after hard braking? Is there contact for most/all of a wheel rotation or only once per?

If it's only making noise under certain conditions, it might not be an issue - could just be debris sticking or temporary heat expansion.

​​​​​​If it's making noise most of a revolution, you probably need to align your caliper. If it's only one spot, truing (bending it straight) is in order. Both are easy jobs.

surak

Piston could also be sticky, especially if it rubs after braking some but not all the time.

Shinkers

If the rotor is bent than the noise should be present if you lift the front wheel up and spin the wheel. If that's the case, you can bend it straight with your fingers (wear a glove or use a clean paper towel or similar to keep the rotor clean).

I've seen some hub designs that allow enough flex in the bearing preload to cause rotor rub during high efforts (this is unlikely to be your problem though).

If it's a noise that only shows up sometimes, than it could be a sticky piston, debris, or just the rotor getting hot. I've noticed on my mountain bike that if I get the rotors hot I noticed a bit more rubbing as they start to warp (I'm assuming) but then quiet as they cool.

jpescatore

First check that your pads are centered around the rotor - easy to do yourself, many YouTube videos show how. I don't rubbing often from my disc brakes, but every time except 1 this fixed it.

The one time was a gunked up and sticky piston. I watched YouTube videos on how to clean that up, a bit trickier and messier - but that cleared up the one time issue.

DaveSSS 

I would check the rotor for runout first. Park makes a truing gage, but it's crude without a dial indicator to go with it. I made my own with some aluminum angle I had laying around and a dial indicator I've had since the 80's. My Campy rotors are still true to .002 inch. An adjustable wrench may work as well as a truing fork, but so far I've never needed to true a rotor. If a rotor needs repeated truing, I'd replace it.


https://www.parktool.com/product/rot...ategory=Brakes
https://www.parktool.com/product/dia...ategory=Brakes
https://www.parktool.com/product/rot...ategory=Brakes

ericcox

+1 to all off the above. I will note that when Chris Froome's complain about disc brakes went up, I had a set of Swiss Stop catalysts rotors on the way. Damn if he isn't right - those rotors do get a little noisier than Shimano rotors when they heat up. They seem a little quieter in the wet, though. Not sure how that works...

I do think the easiest starting point is to center the caliper and then move from there. That takes a few minutes tops and is super easy. If that doesn't work, then move up the chain of difficulty.

remlapnonrev

Agree with everything that has been said. If it is an intermittent sound, probably a bent disc. If it's constant, it could be debris. I know if I have been riding in rainy conditions, I get squeak breaks because of dried detritus on the disc.