ajbarickman

I just bought a Canyon Ultimate CF SL 8.0 aero which has disc brakes. It's my first bike with disc brakes so I am ignorant of how to adjust or fix a problem I am having. The brakes both spin freely without rubbing when on a stand or when riding normally. When I stand out of the saddle I hear the front disc start rubbing on the caliper.

I have tried a few things:

1. Remove the wheel and remove the disc. Reattach the disc and ensure it's tight and properly put on. Remount
2. Loosen the mounting screws for the front caliper, pull on the lever, while holding tighten the screws for the caliper.
3. Bend a business card over the disc when removed from the bike. Put the wheel back on the bike with the business card between the pads to act as a spacer. Repeat step 2. Remove business card.

None of these steps have solved the problem. The disc has a very slight wobble but nothing major and it does not rub until I stand out of the saddle.

Please help a disc brake noob like me. Thanks!

Robert A

Have you checked the tightness of your headset and the front hub? I wonder if either are lose, would it cause some pad/disk misalignment when you stand.

SalsaShark

This happens on one of my bikes, and seems to be caused by the flexing of the frame and fork when applying excess power.
It sounds like you have the caliper and pads aligned properly with the rotor. However, your business card spacer will not change anything unless you adjust the pad clearance with respect to the rotor; this is not done by loosening and readjusting the caliper mounting screws, but instead is typically performed with a rotary adjustment knob or screw found on the side of the caliper itself. If you are experiencing the rotor rubbing the pads when applying excess power through the bike, the pads likely need to be moved slightly further away from the rotor, giving adequate clearance. You will end up having to squeeze the brake lever a bit more before the pads engage the rotor, but should still have adequate brake power and modulation. If you want the pads to engage the rotor immediately when the levers are pulled only slightly, i would recommend truing the rotor as perfectly as possible, and being prepared to live with a small degree of brake rubbing when out of the saddle - this has been my experience.

Canker

Try the business card trick again only put it on one side and then try and standing and see if it rubs. If it does do the card trick but on the other pad and try again. You may just have to do it the manual way by eyeballing it. You need a hair more clearance on one side.

jadocs

He has hydraulic disk brakes I am sure, not mechanical. There is no individual caliper adjustments.

It’s possible that there is flex, it also could be wheel flex.

OP you may have to manually center the caliper by hand, not loosening the screws and applying the brake. Your hydraulic hose is not going to allow much movement using that technique and can prevent true centering of the caliper. Doing it manually by hand means moving the caliper the opposite direction of the rub then tightening the bolts before releasing. You check it by applying the brakes and observing the distance between the brake pad and disc once it is released. You may have to do this a few times. The objective is to achieve uniform space between pad and disc once brake is applied and released. Barring that you may need to get the rotor replaced with one that does not have a wobble.

Dean V

I would ride it for a few weeks and see if improves with the pads bedding in.
My Domane did.

MoAlpha

Having had this problem, my advice is first to clean, lube, and work the pistons to make sure they’re retracting; use the brake activation method to get the alignment close; and then eyeball and fine tune to compensate for the inevitable asymmetry. Visibility is enhanced by placing a light source or a white background below the caliper. A little patience should solve the issue. Good luck!

eduskator

Looks like frame / fork material flexing... You might want to try buying new components (disc and/or brake pads) to see if the noise stops?

Increasing the distance between the pads & disc might also work, but you will have more travel on your brake lever. Personally, I like it to be as less as possible.

inspclouseau

As others said, it's probably fork or wheel flex. Evident by it only happens when you stand. Not sure how bad it is, but I've run disc brakes on two bikes for the past few years and there was always a slight rub when getting out of the saddle and hitting it hard. I'm also weighing in at 190lbs.

As someone said above, manually center the caliper, let it bed in a bit, and hope it becomes tolerable.

Since it only happens when you stand, probably nothing you can do.

Have no idea what new components would do, but not a reason I'd just buy new ones.

SalsaShark

Aaahhh...my bad. Eyeballing the caliper centering is probably the best solution, then. I find with the bike in a stand, if you can put a bright light to illuminate behind the caliper, it helps to see the gap between the pads and rotor looking from above, making this adjustment (and any rotor truing) a bit easier to achieve.

u235

First thing I'd check.. side to side play of your front wheel when all mounted up. Possibly needs some adjustment and tightened up on the axle. After that...
You said your disc has a slight wobble. That slight wobble combined with the flexing of "things" while out of the saddle is probably adding up and causing your rubbing. Try to straighten out the disc. Often you can fix a slightly warped disc like that with your hand. Find the area that is out of round, place a clean cloth over that section of the rotor and simply push or pull on the disc with your thumb depending on the wobble direction. The exact pressure depends but you can experiment. A slight rubbing is often just a noise. Yes it is rubbing, yes it is annoying, yes something is not right but a single side slightly scraping a rotor at times is not actually that impactful. It's not near the same as a softer compound rim brake pad further out the wheel rubbing from say a slightly bent wheel. I'd still fix it though.
Another option.. swap front and rear discs. Maybe the current back one is more flat just enough to not scrape. Last resort, maybe your front wheel is "lose", axle is not tight or seated correctly or ill fitting or not clamping correctly and has too much movement.

WhyFi

In addition to truing the rotor and aligning the caliper, pay attention to how much you're tightening the thru axle.

People that have switched over to Robert Axle Project axles frequently report the elimination of, or at least fewer problems with, brake rub. Many attribute the improvement to tighter tolerances, but I wonder if more precise tightening (you need a 6mm hex and they specify a certain torque value) is the main factor.

eduskator

200lbs here and my TCR holds just fine. My old Defy held pretty good as well. These things can withstand hoomans weighting up to 300lbs if I'm not mistaken. Guess it just needs a little bit of tender loving care!

inspclouseau

And I just noticed it mentioned that the rotor is not true.

So, there's that...

noodle soup

A warped rotor is a common cause of disc rub, and an under-torqued thru axle will contribute to the issue.

inspclouseau

Yup. Seems like step 1.

MoAlpha

None of my rotors are dead nuts true. None of them rub...currently.

WhyFi

You weigh 87 pounds.

Side query: does your R3 have regular thru axles or the RATs?

u235

Most rotors are slightly out of round. The more I think about the OP's issue, the more it is leaning towards the wheel on axle movement maybe combined with a partially warped rotor. A warped rotor is fine on its own but add in the stack tolerance of some wheel movement, even a sliding wheel on an axle can be noisy on a perfectly straight rotor. The noise is similar to a warped rotor and not constant but instead of making a noise related to rotor rpm, it is only when the bike is swung to the side. I wonder if there is any rubbing on hard turning. Rubbing is a relative term here, even a slight touch of a pad on a rotor can make a lot of noise.

MoAlpha

144 lbs. of spring steel and rawhide, buddy.

Regular.

tyrion

I wonder if a more rigid (i.e. heavier) thru-axle would have any impact.

(just wild guessing)

RiceAWay

This is not uncommon on full suspension MTB's from play in the suspension components. Most of the road bikes that use disk brakes are stiff enough but depending on the axle size the axles themselves can have play in them. This is why they've gone to huge bolt through axles.

ajbarickman

I don't notice any rubbing during cornering. It definitely could be another noise it is hard to tell.

ajbarickman

Thank you all for the quick and super useful feedback.

I think my next steps are going to be 1) Clean and check that the pistons are working properly 2) Adjust the centering by eye to provide the most tolerance 3) Swap front and read rotors to see if anything changes. 4) Increase the distance between pads so that there is more room to accommodate any movement.

jadocs

If you have center lock discs swapping will be easy. If not make sure you know the sequence and torque spec for the bolts.