Repair guides › Drivetrain

Remove and install square-taper cranks

Crank arms that press onto a tapered square spindle. Simple, cheap and still very common. A bolt draws the arm up the taper until it is tight. Removing it needs a crank puller that pushes the arm off the spindle. Crank length (usually 165–175 mm, stamped inside the arm) changes leverage and knee bend.

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Tools

• Ball-end hex key set (1.5–10 mm): Park Tool HXS-1.2 Professional L-Shaped Hex Set ($$)
• 1/4" click torque wrench (about 2–17 Nm) + bits: Pro Bike Tool 1/4 inch drive click torque wrench set (2.2–16.9 Nm) ($$)
• Bike grease: Park Tool PPL-1 PolyLube 1000 ($)
• 12" adjustable wrench: Crescent 12 inch adjustable wrench ($)
• 3/8" click torque wrench 10–60 Nm: Pro Bike Tool 3/8 inch Drive Click Torque Wrench Set 10-60 Nm ($$$)
• 3/8" ratchet + 14/15 mm sockets + 8 mm hex bit: TEKTON 3/8 inch drive socket set metric ($$)
• Square-taper crank puller: Park Tool CCP-22 ($)

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Steps

1. Remove the dust cap (if any) and the crank bolt (8 mm hex or 14/15 mm socket).
2. Back the puller's push-rod all the way out first. Thread the crank puller body FULLY into the arm threads: at least 5 full turns by hand. Partial threading strips the arm.
3. Turn the puller's inner push-rod clockwise. It presses on the spindle and pops the arm off.
4. Install: clean the taper (Park Tool: leave the taper clean and dry; grease the bolt threads and under the bolt head. If it still creaks at full torque, some mechanics add a thin film to the taper), slide the arm on at 180° from the other arm.
5. Grease the bolt threads, torque. Re-check after the first ride: square tapers settle.

Torque

Diagram

Signs it needs doing

• Creak or click once per pedal stroke
• Crank arm wobbles (loose bolt; ride it loose and you ruin the arm)
• Pedal threads stripped

Problems this fixes

• Clicking or ticking when pedaling
• Pedal or crank feels loose or wobbly