What You Need to Do

Replacing bicycle pedals takes about 15 minutes and requires only two tools: a pedal wrench or a 15mm wrench, and an adjustable wrench or Allen key if your pedals use hex bolts instead. You remove the old pedals by turning the wrench counterclockwise — but the left pedal has a reverse thread, so you turn it clockwise. Then you screw the new pedals in by hand first, tighten them firmly, and you are done. The whole job is mechanical, not technical, and you do not need to remove the crank or chain.

The reason people hesitate is the reverse thread on the left side. It exists because pedals spin forward, and a normal thread would loosen itself over time. Once you know that detail, the job becomes straightforward.

Key Takeaways

  • The left pedal has a reverse thread and turns clockwise to loosen, while the right pedal turns counterclockwise like a normal bolt.
  • A 15mm pedal wrench or adjustable wrench is the only tool you need; the job takes 10 to 15 minutes.
  • Always hand-tighten first to avoid cross-threading, then use the wrench to tighten firmly but not with maximum force.
  • Pedals come in two axle sizes — 9/16 inch and 1/2 inch — so measure your old pedal axle or check your bike's manual before buying new ones.

Identifying Your Pedal Size Before You Buy

Bicycle pedals come in two standard axle sizes: 9/16 inch and 1/2 inch. Most adult bikes use 9/16 inch; most children's bikes and some older or budget models use 1/2 inch. If you buy the wrong size, the pedal will not thread into the crank arm at all.

To check your size, look at the axle — the metal rod that sticks out from the pedal body. If you have the old pedal still attached, measure the diameter with calipers or a ruler. If you have already removed it, measure the hole in the crank arm where the pedal screws in. Your bike's manual or the manufacturer's website will also list the size. When you buy new pedals, the package will state the axle size clearly.

Removing the Old Pedals

Position your bike so the crank is straightforward to reach — either in a repair stand or leaning against a wall. Locate the right pedal (the one on the right side when you sit on the bike facing forward). Place your 15mm wrench on the flat part of the pedal axle, the part that sticks out from the crank arm. Turn the wrench counterclockwise — the same direction you would turn any normal bolt to loosen it.

Once the right pedal is loose, unscrew it by hand and set it aside. Now move to the left pedal. This one has a reverse thread, which means you turn it clockwise to loosen it — the opposite of what feels natural. Place the wrench on the left pedal axle and turn clockwise. Once it is loose, unscrew it by hand. Both pedals should come free without excessive force; if one is stuck, explore penetrating oil and wait 10 minutes before trying again.

Installing the New Pedals

Before you use the wrench, hand-tighten both new pedals. Start with the right pedal: screw it into the right crank arm by hand, turning counterclockwise (the normal direction). Go slowly and feel for resistance. If you feel grinding or the pedal does not turn smoothly, stop when ready — you may have cross-threaded it. Back it out, line it up again, and start over. Once it is hand-tight, move to the left pedal and repeat, this time turning clockwise by hand.

After both pedals are hand-tight, use your wrench to tighten them fully. Place the wrench on the right pedal axle and turn counterclockwise until the pedal is snug. Do the same for the left pedal, turning clockwise. You want them tight enough that they do not move when you push on the pedal, but you do not need to use all your strength — over-tightening can strip the threads in the crank arm.

Testing Your Work

Spin the pedals by hand to make sure they rotate freely and do not rub against the frame or chain. Sit on the bike and push down hard on each pedal to confirm they do not move or creak. If a pedal feels loose or makes noise, tighten it a quarter turn with the wrench and test again.

If a pedal creaks even when tight, the creak is usually coming from the pedal bearing itself, not the connection to the crank. This is normal wear and means the pedal bearing will need replacement eventually, but it does not affect safety. Ride the bike for a few minutes to confirm everything feels right, then you are finished.

Pedal Types and What They Mean for Replacement

Flat pedals (also called platform pedals) are the most common and the easiest to replace — they are what most people picture when they think of a pedal. Clip-in pedals, which lock your shoe to the pedal, replace the same way but require you to also buy compatible shoes. Pedals with cages (metal or plastic boxes around the flat surface) also replace identically; the cage is just part of the pedal body.

The replacement process is the same regardless of pedal type. The only difference is comfort and function once they are installed. If you are switching from flat to clip-in or vice versa, the mechanical replacement is identical — you are just choosing a different pedal body to screw in.

What to Do If a Pedal Axle Breaks Inside the Crank

If the axle snaps and part of it stays stuck in the crank arm, you cannot straightforward screw in a new pedal. The broken piece must be removed first. A bike shop can extract it using a specialized tool called a pedal extractor or by carefully drilling it out. This is not a job to attempt at home without the right tool, because drilling incorrectly can damage the crank arm permanently.

If this happens, take the bike to a shop rather than trying to force a new pedal in. The cost of extraction is usually between $20 and $50, depending on how stuck the piece is. Once it is out, you can install new pedals normally.

Frequently Asked Questions

Can I use a regular wrench instead of a pedal wrench?

Yes. A 15mm adjustable wrench or a 15mm open-end wrench works just as well as a pedal wrench. A pedal wrench is thinner, which makes it easier to fit in tight spaces near the crank, but it is not required. If you have an adjustable wrench at home, use that.

Why does my left pedal turn the opposite direction?

The left pedal has a reverse thread to prevent it from loosening as you pedal. Because pedals spin forward, a normal thread would gradually unscrew itself over time. The reverse thread keeps it tight. This is why you must remember to turn it clockwise to loosen and counterclockwise to tighten — the opposite of the right pedal.

What if the pedal is stuck and will not budge?

explore penetrating oil like WD-40 or a similar product around the base of the pedal axle where it enters the crank arm. Let it soak for 10 to 15 minutes, then try again with the wrench. If it is still stuck, soak it overnight. Do not force it with all your strength, because you risk bending the wrench or stripping the threads.

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

It is not required, but a light coat of grease on the threads makes future removal easier and prevents corrosion. Use a small amount — too much grease can make the pedal slip during tightening. If you do use grease, wipe away excess before tightening.

Can I replace just one pedal, or do I have to replace both?

You can replace just one pedal. There is no rule that says both must match or be the same age. If only one is damaged or worn, replace that one and leave the other alone.