Repair guides › Drivetrain

Replace a press-fit bottom bracket

Bearings pressed directly into the frame. Cups or bearings press straight into a smooth frame shell (BB86, BB92, PF30 and others). Removing and fitting them needs an extraction tool and a bearing press.

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Tools

• Ball-end hex key set (1.5–10 mm): Park Tool HXS-1.2 Professional L-Shaped Hex Set ($$)
• 1/4" click torque wrench (about 2–17 Nm) + bits: Pro Bike Tool 1/4 inch drive click torque wrench set (2.2–16.9 Nm) ($$)
• Shop rags + nitrile gloves: shop towels and nitrile gloves ($)
• Bike grease: Park Tool PPL-1 PolyLube 1000 ($)
• Repair stand: Park Tool PCS-9.3 Home Mechanic Repair Stand ($$$$)
• External BB wrench + crank cap tool: Park Tool BBT-9 + Shimano TL-FC16 ($$)
• Press-fit BB press + cup remover: Park Tool BBT-90.3 + Park Tool HHP-3 ($$$)

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Steps

1. Remove the crankset (loosen the left arm's pinch bolts, unscrew the preload cap, slide the arm off, push the spindle out).
2. Note the BB standard printed on the old cups or in the frame manual (for example BB86, BB92, PF30) and buy one that matches the frame and your crank's spindle size.
3. Drive the old cups or bearings out from the inside with the bearing extraction tool, tapping around the edge so each comes out straight.
4. Clean the shell and check it for cracks or a worn, loose fit.
5. Lightly grease the shell (or use the retaining compound the BB maker asks for), then press the new cups in straight with the BB press until they sit fully against the shell faces. Never hammer them in.
6. Reinstall the crankset, set the preload cap until the play is just gone, and tighten the pinch bolts in stages to the crank maker's torque.

Torque

Diagram

Signs it needs doing

• Creak
• Play or roughness when you turn the cranks