You need a crank puller, an Allen wrench, and about 30 minutes

Removing a crankset means taking off both crank arms and the chainrings that sit between them. The job is straightforward if you have the right tool — a crank puller — and becomes difficult without it. Most cranksets come off in this order: remove the crank bolts, use the puller to separate the arms from the spindle, then unbolt the chainrings if you need to. The whole process takes 20 to 40 minutes depending on how stuck the parts are.

The reason cranksets seize is that the crank arm tapers onto the spindle and corrodes over time. Pulling straight out does not work; you need mechanical advantage. A crank puller threads into the arm and pushes against the spindle to force them apart. Without one, you risk bending the arm or stripping the threads.

Key Takeaways

  • A crank puller is the one tool you cannot skip — it costs $15 to $40 and is the only safe way to separate the crank arms from the spindle.
  • Start by removing the crank bolts (usually 14 mm or 15 mm), then thread the puller into the arm and turn the center screw until the arm pops free.
  • If a bolt spins instead of loosening, hold the opposite arm steady with a second wrench so the spindle does not rotate.
  • Chainrings bolt on separately and come off after the crank arms are gone, so you do not have to remove them unless you are replacing them.
  • Corrosion and old grease can make the job harder; penetrating oil left overnight makes stuck cranks easier to remove the next day.

What you need before you start

Gather these items on a workbench before you touch the bike. A crank puller that matches your crank type is non-negotiable. Most modern bikes use either a square-taper puller or a splined puller; check your crank arm or the bike's manual to know which one. A square-taper puller has a hollow center and threads into the arm; a splined puller looks similar but fits a different thread pattern. Do not guess — the wrong puller will not thread in.

You also need an Allen wrench or socket that fits your crank bolts. Most are 8 mm, 14 mm, or 15 mm. A second wrench or socket of the same size helps you hold the opposite crank arm steady while you loosen the first one. A socket wrench or breaker bar gives you more leverage if bolts are tight. Penetrating oil (like WD-40 or Liquid Wrench) and a rag are useful if the crank has not been removed in years.

A bike stand or a way to hold the frame steady makes the job easier. You can also flip the bike upside down, but a stand keeps your hands free. Have a clean rag nearby because old grease will come off the spindle.

Step-by-step removal process

Step 1: Remove the crank bolts. Locate the bolt on the outside of each crank arm, closest to the pedal. Use the correct-size wrench or socket. If the bolt spins without loosening, the spindle is turning too. Hold the opposite crank arm with your second wrench to keep the spindle still, then loosen the first bolt. Remove both bolts completely and set them aside in a safe place.

Step 2: Thread in the crank puller. Screw the puller into the hole where the bolt was. Turn it by hand first to make sure the threads catch; if it does not thread smoothly, you have the wrong puller type. Once it is hand-tight, use a wrench to turn it another quarter-turn or so. Do not force it — the threads should feel smooth.

Step 3: Push the crank arm off the spindle. The puller has a center screw that you turn with an Allen wrench or socket. Turn it clockwise slowly. You will feel resistance as the screw pushes against the spindle. Keep turning until the crank arm suddenly pops free. This usually happens after a few full turns. If nothing happens after 10 or 15 turns, stop and spray penetrating oil around the base of the arm where it meets the spindle. Wait 15 minutes and try again.

Step 4: Repeat on the other side. Unscrew the puller from the first arm, thread it into the second arm's bolt hole, and repeat the process. The second arm usually comes off more easily because you have already loosened the spindle.

Step 5: Remove the chainrings (if needed). Once both crank arms are off, the spindle and chainrings stay together. If you only needed to remove the arms — to replace pedals, clean the spindle, or access the bottom bracket — you are done. If you need to remove the chainrings, unbolt them from the spider (the metal piece that holds them). Most bikes have 4 to 5 bolts per ring. Use an Allen wrench to remove them, working around the ring in a star pattern so you do not bend it.

What to do if a crank is stuck

Corrosion and dried grease can make a crank arm refuse to budge. If the puller is turning but the arm is not moving, stop when ready. Forcing it risks breaking the puller or stripping the threads in the arm.

Spray penetrating oil generously around the base of the arm where it meets the spindle. Work it in with a rag and let it soak for at least 30 minutes; overnight is better. The oil seeps into the corrosion and loosens it. After soaking, try the puller again, turning slowly and steadily. If it still will not move, soak it again and wait longer.

Heat can also help. A heat gun or hair dryer applied to the arm for a few minutes expands the metal slightly and can break corrosion loose. Let it cool before trying the puller again. Never use a torch on a bicycle frame — you will damage the paint and weaken the metal.

Common mistakes that make the job harder

Using the wrong crank puller is the biggest mistake. A square-taper puller will not fit a splined crank, and forcing it strips the threads. Check your crank type before you buy or borrow a puller. If you are unsure, take a photo of the crank arm to a bike shop and ask.

Turning the puller too fast or too hard can break it or damage the crank arm. The puller works by steady pressure, not force. Turn the center screw slowly and let the mechanical advantage do the work. If you feel sudden resistance or hear cracking, stop and reassess.

Forgetting to hold the opposite crank arm steady while loosening the bolts causes the spindle to spin. This makes it hard to remove the bolts and can strip them. Always use two wrenches — one on the bolt you are loosening, one on the opposite arm.

When to take it to a shop instead

If the crank puller threads do not catch, or if the puller spins without pushing the arm, the threads in the arm are stripped. A bike shop can sometimes repair this, but it usually means replacing the crank arm. Do not keep trying — you will make it worse.

If the arm breaks while you are removing it, or if the spindle itself is damaged, the bottom bracket (the part the spindle sits in) may also be damaged. This is a job for a shop because it requires specialized tools to remove and replace the bracket.

If you do not have a crank puller and do not want to buy one, a bike shop will remove the crankset for $20 to $50. This is worth it if you only need the job done once.

Frequently Asked Questions

Do I have to remove the chainrings to take off the crank arms?

No. The crank arms and chainrings are separate. Once the arms are off, the spindle and rings stay together. Remove the rings only if you are replacing them or need to clean underneath them.

What is the difference between a square-taper and splined crank puller?

They look similar but fit different crank types. A square-taper puller works on older cranks with a square-shaped spindle hole. A splined puller works on newer cranks with a splined (grooved) hole. Using the wrong one will not thread in. Check your crank manual or ask a shop which type you have.

Can I remove a crank arm without a puller?

Not safely. Trying to pry or hammer the arm off bends it and damages the spindle. A crank puller costs $15 to $40 and is the only tool designed for this job. Renting one from a shop is also an option.

How tight should the crank bolts be when I put the crankset back on?

Most crank bolts torque to 30 to 40 newton-meters (22 to 30 foot-pounds). If you do not have a torque wrench, tighten them firmly with a wrench until you feel solid resistance, then stop. Over-tightening strips the threads; under-tightening lets the arm slip. A bike shop can torque them correctly if you are unsure.

Why does my crank arm keep coming loose after I reinstall it?

The spindle taper may be dirty or corroded. Before reinstalling, wipe the spindle and the inside of the crank arm with a clean rag to remove old grease and corrosion. A thin coat of fresh grease on the taper helps the arm seat properly and stay tight longer.