How to Remove a Bike Crank

Crank removal is the one job in this hub where the tool genuinely matters, and where the right tool for one bike will damage another. So the first half of this guide is about working out what you have — that part is not optional.

Identify your crank

Before you start

• Remove the pedals if the crank is coming right off the bike. Remember the left one is reverse-threaded — removing bike pedals covers it.
• Shift the chain onto the smallest chainring to get it out of the way.
• Clean the area around the crank bolt. Grit in the bolt recess makes the Allen key sit shallow and round the head.
• Photograph the assembly, including the order of any spacers and washers.
• Work on the left, non-drive side first on modern external-bearing cranksets. It is the side designed to come off.

Removing an external-bearing crank

This is what most bikes made in the last fifteen years use, and it is the easiest of the three. The left arm clamps onto a splined axle that is permanently attached to the right arm.

Hollowtech II and similar

1. 1

   Loosen the two pinch bolts on the left arm

   Usually 5 mm Allen. Loosen both, alternating a little at a time, and take them out or leave them very loose.

2. 2

   Undo the preload cap

   The plastic cap in the centre of the left arm. It takes a specific splined plastic tool, which is inexpensive and comes with most cranksets. It is only setting bearing preload, so it is barely tight.

3. 3

   Slide the left arm off

   With both pinch bolts loose and the cap out, the arm pulls off the splines by hand. If it resists, check that the pinch bolts are fully loose and that the small retaining tab is lifted clear.

4. 4

   Push the axle and right arm through

   From the left side, push the axle through the bottom bracket. A gentle tap with a soft mallet on the axle end — never on the crank arm — is fine if it is stiff.

Using a crank puller

Square taper and splined cranks are pressed onto the axle by the crank bolt and will not come off by hand. A crank puller is a two-part tool: an outer body that threads into the crank arm, and a centre bolt that pushes against the axle.

What not to do

• Do not hammer the crank arm. Even when the arm survives, the shock load goes straight through the bottom bracket bearings and ruins them.
• Do not lever between the crank arm and the frame. You will mark the frame and may crack the arm.
• Do not ride a bike with a loose crank bolt. A loose square taper arm will deform its own square hole within a few miles, and then it will never sit tight again.
• Do not substitute a bolt or a socket for a crank puller. The tool exists because the force required is genuinely high and needs to be applied squarely.

Refitting

1. 01Clean the axle and the crank arm interface thoroughly. Any grit changes how far the arm seats.
2. 02Whether to grease a square taper is genuinely debated — grease lets the arm seat further up the taper. Follow the crank manufacturer's guidance rather than a rule of thumb.
3. 03Tighten the crank bolt to the manufacturer's torque, commonly around 40 Nm on square taper.
4. 04On external-bearing cranks, set the preload cap only finger-tight — it sets bearing preload, not clamping force — then torque the pinch bolts alternately.
5. 05Re-check the bolt torque after the first ride. Square taper arms in particular settle slightly as they seat, and crank play is one of the things worth testing for during a regular tune-up.