Straightening Your Brake Rotor (Truing)

A warped rotor on disc brakes can cause loud noises while braking and squeaking while riding. Warping can happen from normal use, abuse, or simply by it getting too hot. A bent rotor is often the result of a direct impact when parking or storing the bike. If a rotor is badly bent, it's best to replace it.

It can be hard to determine if your rotor is repairable. If your rotor doesn't show any signs of improving after several minutes of working, then it's probably time to get a new rotor. When a rotor gets too worn it will not be possible to make it straight again. Use caution when working on rotors as their edges can be sharp.

Noise from the brake is often a sign that the rotor needs to be straightened

Before you start, check wheel alignment and play in the bearings. If the wheel isn't seating properly or the bearing allows the wheel to rock, then this is probably your issue, not the rotor.

Other issues that can cause rotor rubbing are:

• Misaligned brake calipers — see How To Adjust Brake Cables.
• Brake mounts on the frame may need to be adjusted / refaced. You will need a special tool for this, or high end bike shops will have it.
• Loose rotor mounting bolts or a loose lockring.

 

Straightening Your Brake Rotor (Truing)

Straightening the rotor can often be done while keeping the wheel on the bike by watching the rotor move through the brake caliper.

Set the bike upside down on the ground in order to get the wheel spinning freely.

Watch for wobble at the caliper between pads. Look for the opening and closing of the gap. Find a section of the rotor that needs truing, and note which way it needs to be bent to correct the runout. Use a flashlight if you need more light.

Rotate this section of the rotor out of the caliper.

Use a rotor truing fork tool to flex the rotor in the appropriate direction in order to improve the bend. Always begin with a small amount of effort on the tool, and then apply more effort if no improvement is seen.

Spin the wheel and sight the rotor again. Repeat as necessary. When the rotor is not rubbing the pads as it spins, it is adequately straight.