Repair guides › Brakes

Replace a rotor / upsize 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

• 1/4" click torque wrench (about 2–17 Nm) + bits: Pro Bike Tool 1/4 inch drive click torque wrench set (2.2–16.9 Nm) ($$)
• Torx key set (T10–T50): TEKTON long arm Torx key set T10-T50 ($)
• Isopropyl alcohol 91%+: isopropyl alcohol 91% ($)
• Blue threadlocker + anti-seize: Loctite 242 Blue and Park Tool ASC-1 anti-seize ($)

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Steps

1. Remove the wheel and the six T25 bolts.
2. Fit the new rotor with the arrow pointing in the direction of rotation.
3. Add blue threadlocker (unless the bolts are pre-treated). Tighten in a star pattern in two passes.
4. For a bigger rotor, add the matching caliper adapter (e.g. 160→180 mm) first. Check the fork or frame maker's maximum rotor size first. Replace any rotor below the minimum thickness stamped on it (usually 1.5 mm; SRAM 1.55 mm).
5. Clean with alcohol, bed in.

Torque

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)

Related jobs

• True a bent rotor