Hub problem or brakes?

[wheezy]

I'm having a small issue with (I think) my hub.

I have disc brakes, and I've noticed when I stand up and put some power through the rear wheel, I can hear the brake rubbing in time with the right pedal stroke. I had the same thing occur on an old derailleur bike, and the problem was fixed by tightening the cones in the rear hub. Is it possible that something similar could be going on here, or could this not happen with the Rohloff?

[expr]

Hi Wheezy,

in the roholff hub the bearings are different from a cone set up. It sounds to me like its just a slight flexing going on between the wheel and the disc pads, I assume that the pads are fixed via a caliper to the rear stay.

I would as a matter of course check to see if the disc screws are tight and that there isn't any side to side play in the wheel (unlikely) for the latter.

Dave.

[wheezy]

Hi Dave,

Thanks for that! Very useful. Yes, the caliper's mounted on the seat stay, and everything's tight there.

I couldn't find any wheel movement at all, but I found I was able to cinch all the disc bolts a few degrees.

I'll report back when I've had a chance to get it out and test it.

[expr]

you may just find that the caliper/ pad clearance on the disc is such that its a natural occurrence, in as much as when an amount of pressure forced to the rear wheel (further accentuated ) by out of the saddle grunt will cause this to happen regardless. I've had bikes where if they have had standard caliper brakes fitted and the pad to rim gap has been so slight that the rim would touch the pad on each downward stroke.

Possibly the only way to alleviate the problem is either (depending on hydraulic or cable) is to slacken the gap off pad to disc or check the tension off (all) of the spokes? to take any flex out... 

[Danneaux]

Hi wheezy,

I was able to solve this same problem on a friend's disc-equipped derailleur bike recently. His cones were properly adjusted without play. Like yours, his disc only rubbed/squeaked when he pressed down on the right pedal. This was a clue the rubbing was torque-induced. As it happened, there were two problems that caused this:

1) A simple removal and reinstall of the wheel showed the QR was fine for securing the wheel, but allowed a minuscule amount of movement of the hub in the vertical dropout under load. Tightening it took out most of the rubbing. His pads were set a bit close, and the wheel wasn't perfectly even in the slots. It didn't take much to put one pad too close to the runout of the disc.

2) While the bike was in the stand, I centered the caliper by loosening it, then turning the cranks, leaving the bolts slightly loose, then tightened them up while still turning the cranks.

This did the trick. Perhaps there's something in there that might resolve your disc-rubbing issue, too.

Best,

Dan.

[wheezy]

...and he's back.

Thanks, chaps, for the input. All very useful (though I don't have a clue about spoke tensioning).

But it looks like I was mistaken about which disc is rubbing. I didn't think it likely that pedalling hard would affect the front wheel, so I've been looking in the wrong place. I could have sworn the sound was coming from where i expected it to be coming from.

Solving the problem should be a little more straightforward now.

And the good news is all my disc bolts are safely tightened.

[Danneaux]

But it looks like I was mistaken about which disc is rubbing.

No worries, wheezy! Bike sounds are notoriously hard to locate, define, and resolve because the noises telegraph so efficiently throughout the frame and components. I spent hours looking for a BB creak on a friend's bike, when it turned out a slightly loose saddle clamp on the seatpost was the real culprit.

We've all been there. If it is still a problem, give a shout and we'll weigh in with suggestions.

Best,

Dan.

[il padrone]

I've spent some time trying to track down a clicking crank, tightening everything, only to discover it was a somewhat loose EBB tension bolt.

The worst thing is.... then it has all happened again