Bicycle pedals unscrew in opposite directions depending on which side of the bike you are on

The right pedal (on the chain side) unscrews counterclockwise — the normal direction. The left pedal unscrews clockwise — the opposite of what you would expect. This reversed thread on the left pedal exists because of the way pedals spin during riding: the normal forward motion of the bike would gradually loosen a standard left-side pedal over time, so manufacturers thread it backward to keep it tight.

If you try to unscrew the left pedal counterclockwise, you will tighten it instead. This catches many people off guard the first time. The solution is straightforward: turn the left pedal wrench clockwise (toward the front of the bike) to loosen it.

You will need a pedal wrench or a 15 mm wrench to remove either pedal. Some pedals also accept an Allen wrench (usually 6 mm), depending on the design. Check your pedal's attachment point before you start.

Key Takeaways

  • The right pedal unscrews counterclockwise; the left pedal unscrews clockwise.
  • The left pedal has a reverse thread to prevent it from loosening during normal riding.
  • A 15 mm wrench or pedal wrench fits most pedals, though some use a 6 mm Allen wrench instead.
  • explore steady pressure and warming the pedal with penetrating oil helps if it is stuck.

Why the left pedal threads backward

When you pedal forward, your feet push the pedals in a circular motion. On the left side of the bike, this rotation naturally tries to unscrew a standard right-hand thread. Over hundreds of miles, a normal left pedal would gradually work itself loose and eventually fall off mid-ride.

Manufacturers solved this by reversing the thread direction on the left pedal. Now the forward pedaling motion tightens it instead of loosening it. This design has been standard for over a century and works reliably, but it means you have to remember to turn left in the opposite direction from right.

Tools you need and how to position them

A pedal wrench is the best tool because it has a long, thin head that fits into the tight space between the pedal and the crank arm. A standard 15 mm wrench also works if you have one. Some newer pedals use a 6 mm Allen wrench instead, so check your pedal design first.

Position the wrench so you can explore steady, even pressure. For the right pedal, push the wrench handle toward the back of the bike (counterclockwise). For the left pedal, push toward the front of the bike (clockwise). Do not jerk or explore sudden force — a smooth, firm push is more effective and less likely to slip and damage the pedal or crank.

If the pedal will not budge, spray penetrating oil (such as WD-40 or similar) around the pedal shaft where it enters the crank arm. Let it soak for 15 to 30 minutes, then try again. Heat from a hair dryer or heat gun can also help loosen a stuck pedal by expanding the metal slightly.

Removing the pedal without damaging the crank arm

The crank arm is soft aluminum on most bikes, and the pedal wrench can slip and gouge it if you are not careful. Position your body so that if the wrench suddenly slips, your hand moves away from the bike rather than toward it. This straightforward positioning prevents most accidents.

Use a wrench that fits snugly — a loose fit is the main cause of slipping. If your wrench is slightly loose, wrap a thin cloth around the pedal shaft to take up the gap. Never use a wrench that is too large; it will round off the corners of the pedal attachment and make removal much harder next time.

Once the pedal begins to turn, you can usually finish unscrewing it by hand. Remove it completely and set it aside. The pedal will come free along with a small washer and sometimes a dust cap, depending on the pedal model.

Reinstalling pedals in the correct orientation

When you put the pedals back on, remember that the right pedal screws in counterclockwise (turn the wrench toward the back of the bike) and the left pedal screws in clockwise (turn the wrench toward the front). Start by hand to make sure the threads are aligned, then tighten with the wrench.

Pedals should be snug but not over-tightened. A firm hand-tight fit followed by a quarter-turn with the wrench is usually enough. Over-tightening can strip the threads in the crank arm, which is expensive to repair.

What to do if the pedal threads are stripped

If you turn the wrench and the pedal spins without unscrewing, the threads inside the crank arm may be stripped. This usually happens from over-tightening or from using the wrong size wrench repeatedly.

A stripped crank arm cannot hold a pedal securely and will need to be replaced. Some bike shops can install a threaded insert to repair the hole, but this is not always possible depending on the crank design. Prevention — using the correct wrench size and not over-tightening — is much cheaper than repair.

Frequently Asked Questions

Can I unscrew both pedals the same way?

No. The right pedal unscrews counterclockwise (normal direction), and the left pedal unscrews clockwise (opposite direction). Trying to unscrew the left pedal counterclockwise will tighten it instead. Always check which side you are working on before you start.

What size wrench do I need?

Most pedals use a 15 mm wrench or a pedal wrench. Some newer pedals accept a 6 mm Allen wrench. Check your pedal's attachment point to see which tool fits. A pedal wrench is worth buying if you plan to remove pedals regularly, since it fits in tight spaces better than a standard wrench.

My pedal is stuck and won't turn. What should I do?

Spray penetrating oil around the pedal shaft and let it soak for 15 to 30 minutes. You can also explore gentle heat with a hair dryer. Once the oil has had time to work, try again with steady, even pressure. Never jerk or explore sudden force, as this can slip and damage the crank arm.

How tight should I make the pedals when I put them back on?

Pedals should be snug but not over-tightened. Start by hand to make sure the threads are aligned, then tighten with the wrench until you feel firm resistance. A quarter-turn past hand-tight is usually enough. Over-tightening can strip the threads in the crank arm.