Repair guides › Brakes

True a bent rotor

The steel disc the pads grab. Bigger rotors = more power and better heat handling. Held on the hub with six T25 Torx bolts. Common sizes 140/160/180/203 mm. Budget bikes usually run 160 mm front and rear.

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Tools

• Shop rags + nitrile gloves: shop towels and nitrile gloves ($)
• Rotor truing fork: Park Tool DT-2.2 Rotor Truing Fork ($$)
• Isopropyl alcohol 91%+: isopropyl alcohol 91% ($)

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Steps

1. Spin the wheel slowly and watch the gap between rotor and pad through the caliper (hold a white card behind it).
2. Find where it rubs. Mark it with a piece of tape on the tire.
3. Slide the truing fork onto the rotor edge at the high spot. Bend gently in tiny steps. Rotors spring back.
4. Re-check, repeat. Wear clean gloves; finish by wiping with alcohol.

Diagram

Signs it needs doing

• Tick-tick rub once per wheel turn (bent)
• Blue/rainbow tint (overheated)
• Thickness under the minimum stamped on it (usually 1.5 mm; SRAM 1.55 mm)

Problems this fixes

• Brake rubs or scrapes when the wheel spins

Related jobs

• Replace a rotor / upsize rotor