Installing a new set of pedals is one of the most common upgrades for any cyclist, but it is also a task where a small mistake can lead to expensive damage. Whether you are prepping your mountain bike for a muddy trail or setting up a commuter for the week, getting the installation right ensures a safe and silent ride.
You likely want a solution that is quick, effective, and prevents the dreaded “stuck pedal” syndrome in the future. This guide provides the exact steps used by professional mechanics to ensure your pedals stay secure without damaging your crank arms.
We will cover the specific tools you need, the confusing world of reverse threading, and the best practices for how to attach bike pedals so you can get back to the dirt or the road with total confidence.
Essential Tools and Preparation for the Job
Before you get your hands dirty, you need to gather a few basic tools. Most modern bikes use one of two interfaces for pedal installation, and having the correct size is critical for preventing rounded bolts.
First, check the end of the pedal spindle (the axle that goes into the bike). If there is a hexagonal hole in the end, you will need an Allen key, usually in a 6mm or 8mm size. If the spindle has flat edges near the threads, you need a 15mm wrench.
A dedicated pedal wrench is longer than a standard shop wrench, providing the necessary leverage to break loose old pedals or snug down new ones. You will also need a clean rag and a high-quality waterproof grease or anti-seize compound.
- 15mm pedal wrench or a thin-profile open-end wrench.
- 6mm or 8mm Allen (hex) keys.
- Waterproof bicycle grease (lithium-based is a common choice).
- Clean shop rags for wiping down components.
Proper preparation prevents cross-threading, which is when the pedal enters the crank arm at an angle and destroys the soft aluminum threads. Always start with a clean work area and clean components.
Identifying Left vs. Right Pedals
This is where most DIYers run into trouble. Bicycle pedals are not identical; they are side-specific. The right-side pedal (the side with the chain) has a standard thread, while the left-side pedal has a reverse thread.
Look closely at the spindle of each pedal. Most manufacturers stamp a small “L” for left and “R” for right near the threads or on the end of the axle. If you cannot find a letter, look at the slope of the threads.
The right pedal threads slope upward to the right, while the left pedal threads slope upward to the left. Attempting to force a left pedal into a right crank arm will permanently ruin the crank, requiring a costly replacement.
A pro tip from the FatBoysOffroad shop: if you see serrated lines or small ridges on the spindle flange, that usually indicates the left-side pedal. Always double-check these markings before you begin the process of learning how to attach bike pedals to your specific rig.
how to attach bike pedals Without Stripping Threads
The most important rule when learning how to attach bike pedals is to never force the thread. You should be able to tighten the pedal almost all the way by hand before you ever touch a wrench.
Start by applying a generous layer of grease to the threads of the new pedal. This grease serves two purposes: it allows for a more accurate torque reading and prevents the metal-on-metal “cold welding” that makes pedals impossible to remove later.
Hold the pedal at a perfect 90-degree angle to the crank arm. Align the threads and slowly turn the spindle with your fingers. For the right side, turn clockwise. For the left side, turn counter-clockwise.
If you feel any resistance within the first two rotations, stop immediately. Back the pedal out, clean the threads again, and ensure you are using the correct side. Patience here saves you the price of a new crankset.
Once the pedal is threaded in by hand until the flange meets the crank arm, it is time to use your tool for the final tightening. You want the pedal to be snug, but you do not need to put your entire body weight into it.
Understanding the Logic of Reverse Threading
You might wonder why engineers decided to make one side of the bike different from the other. The reason is a mechanical phenomenon called precession. Essentially, the force of your foot rotation would naturally unscrew a standard-threaded left pedal.
By using a left-hand (reverse) thread on the non-drive side, the pedaling motion actually helps keep the pedal tight. This safety feature prevents the pedal from falling off while you are descending a technical trail or cruising at high speeds.
When you are standing over the bike, a simple rule of thumb is that both pedals tighten by turning the wrench toward the front of the bike. Conversely, both pedals loosen by turning the wrench toward the rear of the bike.
Visualizing this “forward to tighten” rule is the easiest way to remember the direction when you are in the middle of a trailside repair. It eliminates the confusion of clockwise versus counter-clockwise when you are looking at the bike from different angles.
Cleaning the Crank Arm Threads
Before the new pedal goes in, the crank arm needs attention. Take your clean rag and wipe out the internal threads of the crank arm. Grit, old grease, and metal shavings can interfere with the new installation.
If the threads look flattened or damaged, you may need to run a “tap” through them. This is a specialized tool that cleans and restores thread geometry. Most local bike shops can do this for a small fee if you aren’t ready to buy the tool yourself.
A clean interface ensures the pedal sits flush against the crank. If there is a gap, the pedal can wiggle under load, which eventually wallows out the hole and ruins the arm.
The Role of Pedal Washers
Some high-end carbon fiber cranks require the use of a small, thin metal washer between the pedal spindle and the crank arm. Check your manufacturer’s manual to see if these are necessary for your setup.
These washers prevent the hard steel spindle from “digging” into the softer carbon or aluminum material. If your pedals came with washers, use them. They help distribute the clamping force evenly and prevent creaking sounds during hard efforts.
If you are riding off-road, these washers also act as a secondary barrier against moisture and grit. For FatBoysOffroad enthusiasts, preventing creaks is the key to a focused and enjoyable ride on the trails.
Step-by-Step Installation Guide
- Prepare the Bike: Place your bike in a repair stand or lean it securely against a wall. Shift the chain into the largest chainring to protect your knuckles from the sharp teeth if the wrench slips.
- Identify and Grease: Locate the “L” and “R” marks. Apply a thin, even coat of grease to the threads of both pedals. Do not skip this step, as dry threads are prone to seizing over time.
- Start the Right Pedal: Insert the right pedal (drive side) into the right crank arm. Turn the spindle clockwise (toward the front of the bike) by hand. It should spin smoothly for several rotations.
- Start the Left Pedal: Insert the left pedal (non-drive side) into the left crank arm. Turn the spindle counter-clockwise (also toward the front of the bike) by hand. Again, ensure it spins freely without binding.
- Final Tightening: Use your 15mm wrench or hex key to tighten the pedals. Firm pressure is usually enough (about 35-40 Nm if you have a torque wrench). You want them secure, not fused.
- Wipe Excess Grease: Use your rag to wipe away any grease that squeezed out during tightening. Excess grease attracts dirt and trail debris which can cause premature wear on your components.
After the first ride, it is a smart move to check the tightness again. Components can sometimes “settle” after being subjected to the vibrations of a trail or a long road ride.
Maintenance Tips for Off-Road Riders
For those of us who spend time in the mud and dust, knowing how to attach bike pedals is only half the battle. Maintenance is what keeps those pedals spinning smoothly through the seasons.
After a particularly wet or muddy ride, avoid spraying high-pressure water directly at the pedal axles. This can force water past the seals and wash away the internal bearing grease, leading to a “crunchy” feeling or bearing failure.
Every few months, it is a good idea to remove the pedals, clean the threads, and apply fresh grease. This simple ten-minute task prevents the pedals from becoming permanently stuck due to corrosion from salt, mud, or moisture.
If you notice your pedals have developed “play” (they wiggle on the spindle), it may be time for a rebuild. Many modern off-road pedals, like those from Shimano or Crankbrothers, are serviceable with basic tools and a fresh seal kit.
Keep an eye on the “pins” if you use flat pedals. These small screws provide your grip. If they get rounded off or sheared away by rocks, replace them promptly to maintain your traction and safety on technical terrain.
Choosing the Right Pedals for Your Riding Style
While the method of installation remains the same, the type of pedal you choose significantly impacts your riding experience. Weekend DIYers often start with “flats,” which allow you to move your feet freely.
Off-road enthusiasts often prefer “clipless” pedals, which actually clip into a cleat on the bottom of a cycling shoe. These provide better power transfer and keep your feet from bouncing off the pedals on rough, rocky descents.
For the FatBoysOffroad crowd, a “hybrid” or “platform” pedal offers the best of both worlds. They feature a large surface area for stability and aggressive pins for grip, even when your boots are covered in thick mud.
Consider the environment where you ride most. If you encounter lots of rock strikes, look for pedals with a slim profile and durable aluminum or composite bodies that can take a beating without snapping the spindle.
Frequently Asked Questions About how to attach bike pedals
Can I use WD-40 instead of grease on the threads?
No, WD-40 is a solvent and a light lubricant, but it is not a long-term grease. It will evaporate or wash away quickly, leaving your threads prone to corrosion and seizing. Always use a dedicated bicycle grease or anti-seize compound.
What happens if I cross-thread my crank arm?
If the damage is minor, a bike shop might be able to “chase” the threads with a tap. If the damage is severe, you may need a “Helicoil” insert or a completely new crank arm. This is why hand-tightening at the start is so vital.
How tight should bike pedals be?
Pedals need to be quite snug to prevent them from backing out, but they don’t need “gorilla strength.” If you have a torque wrench, most manufacturers recommend between 35 and 40 Newton-meters (Nm). Without a torque wrench, a firm pull with a long wrench is usually sufficient.
Why is my left pedal turning the wrong way?
The left pedal is reverse-threaded to prevent it from unscrewing itself while you ride. To tighten it, you must turn it counter-clockwise. To loosen it, you turn it clockwise. Just remember: turn toward the front wheel to tighten both sides.
Do I need different tools for different bike brands?
Generally, no. The 15mm wrench and 6mm/8mm hex key standards are universal across almost all brands, including Trek, Specialized, Giant, and others. The threading size (9/16″ x 20 tpi) is also standard for almost all adult mountain and road bikes.
Final Thoughts for the DIY Mechanic
Mastering the art of how to attach bike pedals is a rite of passage for any serious rider. It gives you the freedom to swap gear based on your terrain and ensures that your bike remains in peak mechanical condition.
Always remember the golden rules: clean the threads, use plenty of grease, identify the left versus right side, and start the threading process by hand. These simple steps separate the pros from the amateurs and keep your bike quiet on the trail.
Taking care of your own maintenance builds a deeper connection with your machine. Whether you are hitting a local trail or preparing for a cross-country adventure, knowing your pedals are secure allows you to focus on the ride ahead.
Stay safe, keep your tools clean, and enjoy the satisfaction of a job well done. Happy riding!
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