Which Bike Pedal Is Reverse Threaded: How to remove a pedal and what to do if you do it wrong?


Whether you are removing your pedals to pack your bike into a bike box, or simply swapping them out for the new pair you just bought yourself, removing bike pedals can be a little confusing, As someone who is now experienced in bike maintenance, I thought I would help to clarify which way you need to turn a bike pedal to remove it, as well as which bike pedal is reverse threaded?

The left pedal of a bike is reverse threaded. This means that the threads run the opposite way to normal, meaning you need to turn them clockwise to loosen them. You can easily remove a bike pedal by putting it into the 3 o clock position and pulling the Allen wrench up while your foot is on the pedal.

So, we now know that the left pedal is reverse threaded, but what is the best way to remove a bike pedal? I take a look at this, as well as why bike pedals are reversely threaded in the first place through the rest of the article?

Which bike pedal is reverse threaded?

All bike pedals are designed so that the left side pedal (the non-drive side pedal) is reverse threaded. This means that the ridges running around the pedal run in the opposite direction to a normal screw or the other pedal.

The main concern is that an inexperienced cyclist may try removing a bike pedal with the normal “righty-tight, lefty loosey” technique that works on other screws. This could be disastrous on a bike as it will cause the ridges (threads) on the pedal to damage the ridges inside the crank (the arms that hold the bike pedals), this is called “reversing the thread” on your pedals.

Damaging the thread can make it so that you are permanently unable to screw in the pedal to the crank as the ridges that the pedal has to interlock with have been worn away.

As such, many cyclists can be nervous about removing their own pedals, not only due to the concern of damaging the bike itself, but reverse threading a bike pedal can even invalidate a bike’s warranty in some cases. So how do you actually remove bike pedals?

How do bike pedals come off?

Step 1: Confirm which type of pedal you have

Confirm whether or not your pedals unscrew with a wrench or an Allen key. You can do this by looking through the back of the pedals and seeing if there is an Allen key hole. If there is, then you will need one of these to loosen the pedal, otherwise, you will need to use a wrench.

  • If you require an Allen key, the majority of bikes use an 8mm Allen Key.
  • If you require a wrench or spanner, then the majority of pedals require a 15mm wrench.

Step 2: Put the bike into the highest gear

The next step is to move the bike into the highest gear. This will put the chain around the largest ring on the bike (the one nearest the pedals). This means that the sharp points of the gears are now covered by the chain and you are less likely to scratch or cut yourself on them.

Step 3: Position the pedals and wrench

The first and easiest pedal to remove is the drive-side pedal. This is the pedal on the right side of the bike as you are sitting on it. This pedal is threaded normally and so you can turn the Allen key or wrench as you would expect, turning it left to loosen it.

First of all, put the pedal into the 3 o clock position (so that the pedal is pointing towards the handlebars). Then insert your Allen key or attach your wrench so that it is also directed forward.

Step 4: Unscrew the pedal

Move your front wheel out of the way, put your foot onto the pedal to hold it in place, and then pull the wrench upwards.

This should loosen the pedal enough that you can then simply unscrew the pedal with minimal force.

Why are bike pedals reverse threaded?

So given there is so much extra confusion involved in reverse threaded pedals, why do bike manufacturers do this at all?

The reason that the two pedals of a bike are threaded in different ways is to reduce the effect of precession from loosening or tightening them as you cycle. Precession is a complicated process whereby turning objects don’t act in the way you would normally expect them to.

This works for any object, take for example a pencil held loosely in your fist (you can try it yourself). Spin your fist with the pencil in a circular motion like a pedal. The pencil actually rotates in the opposite direction to the way your fist is rotating.

This occurs because the pencil is thinner than the hole in your fist. This also happens to bike pedals, meaning they rotate in the opposite direction than the way you are pedaling, after all the threads of the pedal are slightly thinner than the internal threads in your crank (the pedal has to fit inside the crank).

By reverse threading one of the pedals, you help to ensure that as you pedal, the pedals are not tightening themselves beyond the point that you would ever be able to loosen them again.

Are all bicycle pedals threaded the same?

All bikes have the same threading pattern, with the right pedal (the drive side wheel) being threaded normally and the left-sided wheel (the non-drive side) being reversely threaded. This is because all bikes pedal in the same direction to go forward and so this reverse threading needs to occur in all bikes to ensure that the pedals do not overtighten themselves.

However, not all bike pedals have the same size of threading. This means that a left-sided pedal will always have a reverse thread, no matter what bike you have, but the size of the gap between threads on the pedals may be different.

This is measured by the threads per inch (TPI) or a bike pedal, which literally just means how many threads rings there are per inch of the pedal screw. The two most common sizes of pedal thread are 9/16 20 TPI and 1/2 20 TPI.

What to do if you turn a pedal the wrong way?

Turning a pedal the wrong way can seriously damage either the pedal or the crank of your bike (the arms that hold the pedals).

This is because if you twist the pedal in the wrong way, the threads of the pedal rub against the threads on the crank and they can break either of them, wearing them away so that you no longer have any thread left to screw into. So what do you do if you’ve screwed in a pedal the wrong way?

First of all, take a look at the threads in the crank. In some cases, the damage may be minor and you may still be able to use the pedal and crank as you would normally. Simply try attaching the pedal as you would normally and see if it works.

If this hasn’t worked, try threading the pedal onto the wrong side of the crank (basically putting it on back to front). This may help to straighten out any damaged thread enough for it to work again. After this, simply take it out and retry putting it on correctly to see if this has worked.

Then, you can then you can try using a toothpick or hair pin to clean the damaged area up. Sometimes the worn-down thread of the crank can get gunked up with the worn-away metal and stop the thread from working. Cleaning out the debris can help with this.

If none of these options works then you may have to take your bike to your local bike shop. Here they will be able to assess the damage and either repair the crank (by redrilling a hole for the pedal) or advise that you need a completely new crank.

Overall

As you can see, removing a pedal from a bike can be a little more complicated than you would imagine. At the end of the day, as long as you use the straightforward process I’ve clarified above, then you shouldn’t have any issues.

Remember that when you are putting the pedals back on, this process is reversed. You should also ensure that the pedals are suitably greased as otherwise, they will be very difficult to remove in the future.

Don’t go using WD-40 instead of grease for this step. Many people make this mistake, however in reality there are only a few areas that WD-40 can work on a bike, you can take a look at my article here to see what they are.

Mark Holmes

30-year-old doctor with an interest in cycling, bikepacking, and statistics.

Related Articles