How To Fix A Bent Disc Brake Rotor, by GCN Tech on YouTube. 8 min 33 s.
- Video length
- 8 min 33 s
- Time to do it
- 20 minutes
- Difficulty
- Easy
- Steps
- 8
What you need
Steps
Spin the wheel slowly and listen for the tick. Watch the rotor pass through the caliper to spot the point where it rubs.
Check the rotor bolts are tight and the wheel is seated fully in the dropouts. A loose bolt or badly seated wheel can look like a bent rotor.
Clean the rotor with a rag and isopropyl alcohol so you can see the bend clearly.
Find the exact bend by holding a straight edge or the tool near the rotor as you turn the wheel. Mark the spot with tape or chalk.
Clamp the truing tool on the rotor next to the bend and gently push the rotor back toward straight. Use small movements, not one big pull.
Spin the wheel again and check the gap on both sides of the rotor. Repeat small bends until the rotor runs true.
If the rotor still rubs, loosen the two caliper mounting bolts slightly, squeeze the brake lever to centre the caliper, then tighten the bolts evenly.
Spin the wheel one last time and listen. If it is silent and the lever feels firm, the job is done.
Tips and common mistakes
Never touch the braking surface with bare fingers, since oil from your skin can make the brake squeal.
Bend in tiny steps and check after each one, because it is easy to push a rotor too far the other way.
If the rotor is deeply creased, cracked or worn below the minimum thickness, replace it instead of straightening it.
Wear gloves when handling the rotor, as the edges are sharp.
Questions
Can I straighten a rotor without a special tool?
Yes, a clean adjustable spanner can work if you grip the rotor gently and apply small pressure. A proper truing tool gives more control and is less likely to damage the rotor.
Why does my rotor keep bending again?
Repeated bends often mean the rotor was hit during transport or storage, or the caliper is not centred. Check the caliper alignment and store the bike so nothing presses on the rotor.
How do I know if the rotor is too damaged to fix?
Look for cracks, deep creases or a worn braking surface. If the rotor is below the manufacturer's minimum thickness, replace it rather than bending it.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
