What you need to remove crank bearings
Removing bicycle crank bearings requires a crank puller — a threaded tool that threads into the crank arm and uses a central bolt to push the crank off the axle. You will also need an adjustable wrench or socket set to fit the crank puller, and possibly a bottom bracket tool if you plan to remove the bearings themselves from the axle after the crank comes off. A workstand that holds the bike steady makes the job much easier, though you can work on the ground if you find the frame.
The specific crank puller you buy depends on your crank type. Most modern bikes use either a square-taper bottom bracket (the older standard) or a cartridge bottom bracket. Some newer bikes use press-fit or threaded cups. Check your bike's manual or measure the hole in your crank arm — square-taper holes are roughly 1/2 inch across, while cartridge systems have different thread patterns. A bike shop can tell you in seconds which puller you need if you are unsure.
Key Takeaways
- A crank puller is the only tool that safely removes crank arms without stripping the threads or damaging the crank.
- You must identify whether your bike has a square-taper, cartridge, or press-fit bottom bracket before buying a puller, because each type requires a different tool.
- The crank puller threads into the crank arm, then a central bolt pushes the crank off the axle — forcing it is the most common mistake.
- Once the crank is off, the bearings themselves stay inside the bottom bracket shell unless you are replacing them, which requires a separate bottom bracket tool.
How to thread the crank puller into the crank arm
Place your bike in the workstand so the crankset is at a comfortable working height. If you do not have a stand, lay the bike on its side on a flat surface. Locate the hole in the center of the crank arm — this is where the crank puller threads in. The hole should be clean and free of dirt; wipe it out with a dry cloth if needed.
Thread the crank puller by hand first, turning it clockwise until you feel resistance. Do not force it — if it does not thread smoothly, you may have the wrong puller for your bottom bracket type. Once hand-threading stops, use your wrench to turn the puller another half-turn or so. The goal is snug, not tight. Over-tightening the puller into the crank arm can strip the threads and ruin the crank.
Pushing the crank off the axle
Once the puller is threaded in, locate the central bolt at the tip of the puller — this is the part that actually pushes the crank off. Using your wrench, turn this bolt clockwise slowly. You will feel resistance as the bolt pushes against the axle and begins to lift the crank arm. Keep turning steadily; the crank should slide off the axle with a smooth motion, not a sudden pop.
If the crank does not budge after a few turns, stop and check that the puller is threaded all the way in and that you are turning the central bolt, not the outer part of the puller. A stuck crank sometimes needs penetrating oil left overnight before you try again. Never hammer on the puller or force it — this breaks the tool and damages the crank.
Removing the crank from the other side
Once one crank arm is off, you can see the axle clearly. To remove the other crank arm, repeat the same process: thread the puller into the second crank arm, then turn the central bolt to push it off. Both sides use the same technique and the same tool.
After both cranks are off, the axle and bearings remain inside the bottom bracket shell. If you only needed to remove the cranks — for example, to replace the pedals or service the chain — you are done. The bearings stay in place and do not need to be disturbed.
When you need to remove the bearings themselves
If you are replacing worn bearings or servicing the bottom bracket, you will need a bottom bracket tool that matches your bearing type. This is different from the crank puller. Square-taper systems use a pin spanner or hook tool to unscrew the bearing cups from the bottom bracket shell. Cartridge systems use a cartridge removal tool that looks like a large socket.
Removing bearings is more involved than removing cranks and usually requires the bike to be completely removed from the stand. Many riders take this step to a bike shop rather than doing it at home, because the tools are specific and the adjustment afterward requires precision. If you are only removing the cranks to work on something else, you do not need to touch the bearings.
Reinstalling the cranks after removal
To put the cranks back on, slide each crank arm onto the axle by hand, making sure the splines or square taper align. Push it on firmly until it seats fully — you should hear or feel a slight click. Then use a wrench to tighten the crank bolt (not the puller, but the bolt that holds the crank to the axle) to the torque specified in your bike's manual, usually between 30 and 40 newton-meters for square-taper systems.
Do not over-tighten the crank bolt. This can crack the crank arm or strip the threads on the axle. If you do not have a torque wrench, tighten until snug and then add a quarter-turn — this is close enough for most home repairs. Check that both cranks are tight before riding.
Common mistakes and how to avoid them
The most frequent error is using the wrong crank puller for your bottom bracket type. A square-taper puller will not fit a cartridge system, and forcing it will strip the threads. Before you buy or borrow a puller, confirm your bottom bracket type by checking your bike's manual or asking at a shop.
The second mistake is over-tightening the puller into the crank arm. The threads in the crank are soft aluminum and strip easily. Tighten the puller by hand first, then add wrench turns gradually. If you feel grinding or hear cracking sounds, stop when ready — you have stripped the hole and the crank may be unusable.
A third error is trying to force a stuck crank without using penetrating oil. If a crank will not move after a few steady turns of the puller bolt, spray the axle with penetrating oil and wait several hours or overnight. Forcing it risks breaking the puller or bending the axle.
Frequently Asked Questions
Can I remove a crank arm without a crank puller?
No. Hammering or prying on the crank arm will damage it beyond repair. A crank puller is inexpensive — usually under $20 — and is the only safe way to remove a crank. If you do not own one, borrow or rent from a bike shop rather than improvise.
What if the crank puller bolt breaks while I am turning it?
Stop when ready and do not try to remove the broken bolt yourself. Take the bike to a shop — they have tools to extract broken bolts without damaging the crank arm. Continuing to work on it risks stripping the hole further.
Do I need to remove the bearings every time I remove the cranks?
No. The bearings stay inside the bottom bracket shell and do not come out when you remove the crank arms. You only need to remove the bearings if they are worn, damaged, or you are servicing the bottom bracket itself.
How do I know if my bearings need replacement?
Spin the crank by hand — if it feels rough, gritty, or has play (side-to-side movement), the bearings are worn. You can also push the crank arm side to side while holding the frame; any movement means the bearings need attention.
Can I reuse the crank puller on different bikes?
Only if the other bikes have the same bottom bracket type. A square-taper puller will not work on a cartridge system. If you own multiple bikes with different systems, you will need different pullers or a universal puller that accepts multiple adapters.