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There is a fair amount of lateral movement of the rotor between the pads in the rear wheel break calipers. I have played about trying to centre the rotor as best as I can to stop the ching noise caused by the rotor touching the pads. It seems to have stopped the noise when turning the rear wheel.

However, I've noticed that when the bike is tilted (as if you were corning the bike whilst cycling) to one specific side the rotor rub returns. There is also a slight rhythmic clicking sound coming from somewhere around the rear hub when spinning the rear wheel. I'm guessing that it may have something to do with a loose or unserviced freehub?

I'm also considering buying a new disc rotor, I am not sure how straight my current one is and couldn't think of a way of testing it without having a wheel truing stand.

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  • A bike store will have rotor truing tools. Probably cheaper to get them to true the rotor.
    – Weiwen Ng
    Oct 2 '21 at 22:45
  • Check for properly tightened quick releases or axle play of the hub.
    – Carel
    Oct 4 '21 at 8:27
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The rotor should be flat and co-planar with the hub mounting face, which should be at a right angle to the axle's center line.

Replacing the rotor won't fix issues with the axle or play in the bearings, so check those out before buying parts.

I've used a dial travel indicator to get a rotor completely orthogonal to the axle, and still had rub because the caliper was slightly damaged.

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I am presuming its very slight rubbing that is not noticeably affecting the wheels free rotation.

What type of bike? FS MTB, super light roadie? Worn bushes or light flexible frame may cause a small amount of auditable rubbing under load. The loss of energy form this is tiny, and as long as its only happening under cornering (when energy loss is occurring though the whole system) its not a concern.

If you want to check rotor for straightness, you can simply use a zip tie on the seat stay (or chain stay), set he tip so its just touching the disk, rotate the wheel and look for a gap opening and closing. A perceptible amount of misalignment is acceptable.

If the disk is true, on possibility is unevenly worn disk pads. While it often possible to adjust the caliper with such pads, it tends to be more sensitive and harder to get right. Pull the pads and check for even wear.

Stick caliper pistons will also cause this, if the pistons are not retracting far enough, the pads remain close to the surface of the disk and rub slightly was things flex. Cleaning the caliper pistons while you have the pads out is a good idea.

How much time you spend comes down to your patience. When that runs out, if you cannot live with the slight rubbing, time to throw money at it. A visit to the LBS, with their skills and tools can pay off, but if the bike has cheap brakes, a new set may be more economical with the benefit of better braking.

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