You can replace bike pedals yourself with two wrenches and no special tools

Bike pedals wear out or break, and replacing them is one of the easiest repairs you can do at home. You need a wrench (usually 15mm, sometimes 9/16 inch), five minutes per pedal, and the knowledge that the left pedal has a reverse thread — it tightens by turning counterclockwise. Most people finish the job in 15 minutes without removing the crank or chain.

The hardest part is usually breaking the old pedal loose, not installing the new one. Once you know which direction to turn and how to brace the crank, the rest is straightforward.

Key Takeaways

  • The left pedal unscrews counterclockwise and the right pedal unscrews clockwise — this is the reverse of almost every other bolt on a bike.
  • You need a wrench that fits the pedal axle (usually 15mm or 9/16 inch) and something to hold the crank steady while you turn the wrench.
  • If a pedal is stuck, spray penetrating oil around the axle, wait 10 to 15 minutes, and try again rather than forcing it and stripping the threads.
  • New pedals come with grease already on the threads, so you do not need to add any before installation.
  • Tighten the pedals firmly but not with all your strength — hand-tight plus a quarter turn with the wrench is usually enough.

What size wrench you need and how to find it

Most pedal axles are 15mm, which is the standard size on road bikes, mountain bikes, and hybrids. Some older or cheaper bikes use 9/16 inch (which is close to 14mm but not identical). The easiest way to know is to look at your old pedal: the wrench size is often stamped on the axle itself, or you can try a 15mm wrench and see if it fits snugly.

If you do not have the right wrench, a bike shop will lend you one or sell you an inexpensive combination wrench. Do not use an adjustable wrench — it will slip and round off the corners of the axle, making the pedal impossible to remove later.

How to remove the old pedals without stripping the threads

Place the bike on a stand or lean it against a wall so the crank is accessible and the bike will not tip. Slip the wrench onto the pedal axle. The right pedal (on the right side of the bike when you are sitting on it) unscrews clockwise — push the wrench handle down. The left pedal unscrews counterclockwise — push the wrench handle up. This reverse thread on the left side prevents the pedal from unscrewing as you pedal forward.

If the pedal does not budge after a firm push, stop. Spray penetrating oil (like WD-40 or a similar product) around the base where the axle enters the crank. Wait 10 to 15 minutes and try again. Forcing a stuck pedal will strip the threads inside the crank, and then you will need a new crank — a much bigger job. Patience here saves money.

Once the pedal loosens, unscrew it by hand the rest of the way. Repeat on the other side. You now have two empty crank arms.

Installing new pedals and getting the thread direction right

New pedals come with a thin coat of grease on the threads. You do not need to add more. Pick up the right pedal (marked R) and insert the axle into the right crank arm. Turn it clockwise by hand until you feel resistance — this is the threads catching. Once it catches, use the wrench to tighten it a quarter turn more. Do not crank hard; the goal is snug, not vice-grip tight.

Pick up the left pedal (marked L) and insert the axle into the left crank arm. Turn it counterclockwise by hand until it catches, then use the wrench for a quarter turn more. The left pedal will feel backwards as you screw it in, but that is correct — the reverse thread is intentional.

Spin the cranks by hand to make sure both pedals rotate freely and do not rub the frame or chain. If they do, the pedals are not fully seated. Unscrew them slightly, make sure the axle is straight, and try again.

When a pedal axle breaks inside the crank

If the pedal spins freely but will not tighten, or if you hear a cracking sound while tightening, the axle threads inside the crank are stripped. This usually happens when someone forces a stuck pedal or uses the wrong size wrench. You have two options: replace the crank arm (a job for a bike shop), or use a pedal with a larger axle diameter if your crank has a second set of threads.

Some cranks have both 15mm and 9/16 inch threads, so if one is stripped you can use a pedal with the other size. Ask at a bike shop whether your crank has this feature before you buy a new crank.

Pedal types and what they mean for replacement

Most casual bikes use platform pedals — flat, straightforward pedals with no clips or straps. These are the easiest to replace because they are all the same size and thread the same way. Road bikes and mountain bikes often use clipless pedals, which require special shoes with cleats. Clipless pedals come in different axle sizes and release mechanisms, so when you buy replacements, match the brand and model of your old pedals if you want to use the same shoes.

If you are switching from platform to clipless pedals (or vice versa), make sure the new pedals have the same axle size as your crank threads. A bike shop can tell you in 30 seconds whether your crank is 15mm or 9/16 inch.

Frequently Asked Questions

Can I replace pedals without removing the crank?

Yes. The pedal axle screws directly into the crank arm, so you only need to remove the pedal itself. You do not need to take off the crank, chain, or anything else. Just brace the crank with one hand and turn the wrench with the other.

What if I cannot remember which pedal is left and which is right?

New pedals are marked L and R on the axle. If you are standing over the bike looking down at the cranks, the right pedal goes on the right side and the left pedal goes on the left side. The reverse threads are built in — you cannot screw them in the wrong way because they will not catch.

Do I need to grease the pedal threads before installing new pedals?

No. New pedals come with grease already on the threads. Adding more grease can make the pedal slip inside the crank or cause it to loosen over time. Install them as they come.

How tight should the pedals be?

Tight enough that they do not move when you push on them by hand, but not so tight that you need a wrench to remove them later. Hand-tight plus a quarter turn with the wrench is the standard. If you strip the threads by over-tightening, you will damage the crank.

What if one pedal keeps coming loose?

This usually means the threads are slightly stripped or the pedal axle is bent. Try removing the pedal, cleaning the threads with a dry cloth, and reinstalling it with a fresh coat of grease. If it still loosens, the crank threads may be damaged and you will need a replacement crank.