You need a crank puller tool and an Allen wrench or socket wrench
Removing a bicycle crank requires two tools: a crank puller (a threaded tool that costs $15 to $40) and either an Allen wrench or a socket wrench that fits your crank bolt. The crank puller does the actual removal by pushing the crank arm off the spindle. Without it, you risk stripping the threads on the crank or damaging the spindle itself.
Most modern bikes use either a square-taper spindle (older and mid-range bikes) or a splined spindle (newer and higher-end bikes). The crank puller you buy must match your spindle type — they are not interchangeable. Check your bike's manual or take a photo of your crank to a bike shop to confirm which type you have before buying.
Key Takeaways
- A crank puller tool is essential; trying to remove a crank without one will damage the crank or spindle.
- Square-taper and splined spindles require different crank pullers, so confirm your spindle type before purchasing.
- The crank bolt must be removed completely before the crank puller can be threaded into place.
- After removal, inspect the spindle for damage or corrosion before reinstalling or replacing the crank.
Remove the crank bolt first
Locate the bolt on the inside face of the crank arm — the side closest to the frame. Use an Allen wrench or socket wrench (typically 8mm, 10mm, or 14mm depending on your bike) to loosen and remove this bolt completely. Keep the bolt in a safe place; you will need it when you reinstall the crank.
If the bolt is stuck, explore penetrating oil (like WD-40) and wait 10 to 15 minutes before trying again. Turn the wrench slowly and steadily rather than forcing it, which can round the bolt head.
Thread the crank puller into the crank arm
The crank puller has a threaded shaft that screws into the hole where the crank bolt was. Screw it in by hand until it is snug — do not use a wrench yet. The puller should sit flush against the crank arm with no gaps.
If the threads feel rough or the puller does not sit flush, stop and inspect the hole for damage. Stripped threads mean the crank cannot be safely removed and may require a replacement crank arm.
Turn the center screw to push the crank off
The crank puller has a center screw that extends inward toward the spindle. Using an Allen wrench or wrench that fits the center screw (usually 6mm or 8mm), turn it clockwise slowly. As you turn, the screw pushes against the spindle and forces the crank arm off.
Turn the screw a quarter turn at a time and pause to check your progress. The crank will pop off suddenly once the pressure is released — do not be startled. If the crank does not budge after several full turns, stop, explore penetrating oil around the base of the crank arm, wait 15 minutes, and try again.
Remove the crank puller and inspect the spindle
Once the crank is off, unscrew the crank puller by hand and set it aside. Look at the spindle — the shaft that was inside the crank arm. It should be smooth and shiny. If you see rust, corrosion, or pitting, clean it with a rag and light oil before reinstalling a crank.
If the spindle is severely corroded or bent, the crankset may need replacement. A damaged spindle will cause the new crank to sit unevenly or wobble.
Repeat for the other crank arm if needed
Most repairs require removing only one crank arm — usually the non-drive side (the left arm). If you need to remove the drive-side crank (the right arm with the chainrings), follow the same steps. You will use the same crank puller for both sides.
If you are replacing the entire crankset, remove both arms and then unbolt the spindle from the frame using a crank bolt wrench or socket wrench. This step is less common and is usually done only during a full crankset replacement.
Reinstall the crank or install a new one
Slide the new or cleaned crank arm onto the spindle, making sure the splines or square taper align. The crank should slide on smoothly without forcing. Insert the crank bolt and tighten it firmly with your wrench — typically to 35 to 55 newton-meters of torque, though your bike's manual will specify the exact amount.
If you do not have a torque wrench, tighten the bolt until it is snug and does not move when you pull on the crank arm, then stop. Over-tightening can strip the threads; under-tightening will cause the crank to slip during pedaling.
Frequently Asked Questions
Can I remove a crank without a crank puller?
No. Attempting to pry or hammer a crank off will strip the threads inside the crank arm or damage the spindle. A crank puller costs $15 to $40 and is the only safe method. Many bike shops will remove a crank for $10 to $20 if you do not want to buy the tool.
What if the crank puller spins but the crank does not come off?
The crank is likely corroded to the spindle. Remove the puller, spray penetrating oil around the base of the crank arm, and wait 20 to 30 minutes. Repeat the process slowly. If it still does not move after two attempts, take the bike to a shop — forcing it further risks breaking the spindle.
How do I know if my spindle is square-taper or splined?
Look at the end of the spindle after you remove the crank bolt. A square-taper spindle has a small square shaft. A splined spindle has multiple thin ridges around it. Take a photo and show it to a bike shop staff member if you are unsure.
Do I need to grease the spindle before reinstalling the crank?
A light coat of grease on the spindle helps prevent corrosion and makes future removal easier. Use bike-specific grease and wipe away excess. Do not use so much that it oozes out around the crank arm.