Disc brake rubbing after wheel change...

cookeeemonster

Ok, new bike, faffing about all day...achieving nothing...

After changing a rear tyre, I put the wheel back on and now the brake is rubbing - but only at a certain point.

This is a new shimano hydraulic disc brake...I literally don't know where to start on adjusting things.

The wheel went off an on a couple of times before it started making the noise...it's driving me mad.

I want an easy life.

Any help much appreciated!!

Pa bike looks lovely...would like to ride it at some point too

meanredspider

Presumably you've checked that the wheel is seated properly. After that, is the disc running true or is it bent?Theoretically, squeezing the brakes on hard and releasing them should centre and space hydraulic brakes. But if the disc isn't running true, it's not the calipers you need to fix, it's the wheel/disc you need to fix.

veronese68

If only at a certain point have you managed to bend the disc? Otherwise, as MRS, says check the wheel is in straight and seated properly.
I take it all was well previously or could it be a problem with initial set up or transport?

cookeeemonster

After getting to the point where to be totally honest, I just wanted to sit down and think about crying...I took the wheel off and put it back on again a couple times an now it's fixed.

You have no idea how stressed I was getting...visions of me taking it to the shop an getting a massive repair bill for bending the rotor or something

Thanks peeps, commuting chat people are by far the best people on bike radar by a long long way!!

meanredspider

I'm glad it's fixed!

Yes - Commuting Chat is the best. Road - Training, Fitness and Health (or whatever it's called) is a vipers' nest :twisted:

Initialised

I've had this a few times, a little more or less pressure on the QR skewers can be all it needs to silence a lightly warped rotor.

Since you changed the wheel the rotor may sit slightly closer or further to/from the hub and be off center, meaning that a slightly warped disc starts rubbing. You've probably fixed the noise but not the underlying cause. So best practice would be so re-align the caliper, especially if you can see the disc being bent by the rotor as you pull the brake lever hard. If you were to do this do this when the rotor is already not you can warp the rotor.

Bending a rotor back to true is fairly simple. Rotor between two planks in a vice, in the oven 200C for a an hour or overnight without extra heat. Or five minutes with a marker pen and an adjustable spanner. Use the marker pen to draw a line around the edge of the disc so you can see where it's rubbing, a few rotations will erase the line. Use the spanner to grip the disc and bend in the middle of the erased line so as to move that section of rotor back in line with the rest. Now that I've done it a few times I can do it by eye and fingers.

meanredspider

Initialised wrote:

Since you changed the wheel

CookeeeMonster wrote:

After changing a rear tyre, I put the wheel back on

He didn't change the wheel, just the tyre - the caliper should be fine - especially as it's hydraulic

cookeeemonster

Cheers yeah just the tyre, and you're right Initialised the skewer pressure seems to be quite important for this sort of thing...something to rememeber for the future.

Initialised in my head I thought the rotor would be pretty sensitive or something and that once bent it should be binned...apparently not

Pufftmw

If you get a rubbing pad, then just ease off the 2 bolts holding the caliper to the hanger and move the caliper until it no longer rubs, then tighten bolts again - simples

(Just make sure you ease off the bolts until the caliper is moveable by a bit of pressure, not completely loosen off)

meanredspider

No - the rotors can be tweaked back into alignment if necessary. Not heard about the oven method and, if I'm honest, I'm a bit sceptical about it, but, certainly, a small adjustable spanner to gently nudge it (better too little than too much) is a good thing

Nicholls2k

Don't bend your rotor yet!

If you find your disc brakes are rubbing:
-check the wheel is on correctly + QRs are suitably tight.
-Loose the two bolts holding the brake to the fork (there may be a cup and cone on the bolt) by 2 turns.
-Press down on the brake and hold the brake on (I use an elastic band)
-tighten the 2 bolts holding the brake to the fork (approx. 2 turns)

This problem is very common in the MTB world.

Sorted.

mrtuk

Nicholls2k wrote:

If you find your disc brakes are rubbing:
-check the wheel is on correctly + QRs are suitably tight.

Is it possible that the problem can be caused by QR's being too tight? I had a similar problem with rubbing on my front wheel - sit the wheel in the forks, and spin it with no problem, but as i tighten the QR it aligns slightly differently, and starts to rub. Any ideas how to resolve?

Initialised

mrtuk wrote:

Nicholls2k wrote:

If you find your disc brakes are rubbing:
-check the wheel is on correctly + QRs are suitably tight.

Is it possible that the problem can be caused by QR's being too tight? I had a similar problem with rubbing on my front wheel - sit the wheel in the forks, and spin it with no problem, but as i tighten the QR it aligns slightly differently, and starts to rub. Any ideas how to resolve?

Not exactly caused by skewer tightness, more that the tightness of the skewer affects rotor position and angle in relation to the center of the caliper so a small, unnoticeable warp starts singing as it now contacts a pad each rotation. Once you do a few tyre changes, puncture repairs you'll get the hang of mounting it "just so". But if you leave the rotor off-centre for too long and over time the rotor may warp more under heat cycling stress during heavy braking, also caliper alignment can go out for example when braking hard over rough surfaces.

Even with a brand new rotor and pads, freshly installed and aligned correctly I can't get my front brake to stop singing during out of the saddle climbs due to fork flex. Stiffer forks and through axles designs should eliminate this.