How to Put on Bike Pedals? | Left and Right Threads Explained

Putting on bike pedals looks straightforward until you realize the left side uses a reverse thread. Force the wrong pedal into the wrong crank arm and you can damage threads on both parts.

Why Left and Right Pedals Thread Differently

Pedals spin forward as you ride, which creates a self-tightening force on the drive side but a loosening force on the non-drive side. Manufacturers solve that with a reverse thread on the left pedal. The right pedal tightens clockwise; the left pedal tightens counterclockwise when viewed from the rider’s seat.

Every pedal has an L or R marking stamped into the spindle, usually near the crank end. Check it before you start. Pedals sold in pairs come boxed left and right separately, and they will not swap.

Tools You Need Before You Start

Grab one of two tools depending on the pedal design. Pedals with wrench flats take a standard 15 mm pedal wrench, which has a long handle for proper leverage. Pedals without flats accept a 6 mm or 8 mm hex key inserted into the spindle from the inside of the crank arm. A thin 15 mm spanner or small adjustable wrench also works on pedals that have flats, though a dedicated pedal wrench gives you more torque for stubborn installs.

You’ll also want grease or anti-seize compound. Threads run dry from the factory, and grease prevents future seizing that turns removal into a fight.

Step-by-Step Installation for Both Pedals

Park Tool’s shop guidance recommends greasing threads heavily before threading either pedal into its respective crank arm. Start with the right side: apply grease, thread the pedal in clockwise by hand, and snug it with your wrench. The left pedal repeats the process with counterclockwise threading, per the same source.

For hex-key pedals, insert the Allen key into the spindle and rotate in the same direction as the appropriate pedal thread until tight, following the pedal manufacturer’s instructions for the correct key size.

• Clean the threads on both pedal and crank arm to remove old grease and debris.
• Apply grease to the pedal threads, covering the full threaded length.
• Thread by hand first. The pedal should spin in smoothly most of the way. Resistance at the start means misalignment — stop and realign rather than forcing it.
• Tighten with the wrench.
• Position the wrench correctly.

Hold the opposite crank arm with one hand while you tighten to keep the crankset from rotating. For leverage, hold the wrench with one hand and press with your opposite arm as a second lever against the pedal body.

Common Mistakes That Ruin Pedals and Cranks

Mixing up left and right is the most common error, and it ends with stripped threads and a trip to the bike shop. Check the L and R markings twice. Forcing a pedal that does not start cleanly damages the crank threads permanently, and cranks are far more expensive to replace than pedals.

Skipping hand-threading is the second mistake. Starting with a wrench multiplies the force behind any misalignment, and cross-threading happens fast. Grease also prevents corrosion between the steel spindle and aluminum crank arm, which is why installing dry threads causes seized pedals later.

Overtightening rounds out the list. The pedal needs to be secure, not crushed into the crank. After your first ride, check both pedals again for tightness — they can loosen during initial use as the grease settles.

FAQs

Which way do you unscrew bike pedals?

Removal reverses the installation direction. The right pedal loosens counterclockwise; the left pedal loosens clockwise, viewed from the rider’s position. A common mnemonic is “backward to loosen” on the left side only, since its reverse thread makes it the opposite of what feels natural.

Do you need a special wrench for bike pedals?

A 15 mm pedal wrench is the standard shop tool, but a 6 mm or 8 mm hex key works on many modern pedals. Pedal wrenches have longer handles than standard spanners, giving you more leverage for stubborn pedals without rounding the flats.

Should you grease new bike pedals before installing them?

Yes. Factory threads arrive without lubricant, and grease prevents the steel spindle from seizing inside the aluminum crank arm. It also makes future removal dramatically easier and protects the threads from corrosion over time.

If you’re upgrading and want to know which pedals perform best for triathlon use, our tested roundup of the best triathlon bike pedals compares the top options side by side.