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Given that pedal threads are different on the left and right pedals: the right side pedal has a right-hand thread (removes counterclockwise, installs clockwise); the left side pedal has a left-hand thread (removes clockwise, installs counterclockwise), I often find myself trying to remember which way to turn the wrench to loosen a pedal.

Does anyone have a good-- preferably humorous and easy to remember-- mnemonic device to forever ingrain in my memory which pedal goes which way and keep me from over-tightening when I am trying to loosen?

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I usually pull-up my laptop and look at one of the numerous videos on youtube to get it right.... –  Chmouel Boudjnah May 27 '11 at 12:07
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There can be additional confusion if you're using an Allen wrench on the inner side of the crank. So remember that all of the mnemonics assume you're using a pedal spanner. –  amcnabb Jul 26 '13 at 17:35

22 Answers 22

up vote 27 down vote accepted

What could be simpler than remembering that the left-hand pedal has left-hand thread?

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It helps that the right side is where the drivetrain is. The side with all the mechanical stuff is the one that got it "right". The oposite side, like lefties everywhere, is all alone and "backwards". (Apologies to lefties everywhere.) –  Neil Fein May 27 '11 at 17:36
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@NeilFein - There's a sinister tone to your comment. (Or was it intended to be a left-handed compliment?) –  Daniel R Hicks Dec 8 '12 at 18:01
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Sorry if it came across badly; that wasn't my intent, but I can see how that would be the case. It's a mnemonic that works, is all. I have no objection to deleting my comment if people find it offensive. –  Neil Fein Dec 8 '12 at 20:08
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For reference: I'm pretty sure Daniel was just enjoying some quality puns, and there's nothing in your comment to worry about. –  Useless Dec 11 '12 at 16:12
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@DanielRHicks You're a punny guy. Sinister is derived from the Latin "sinistra" which means "left-hand," and according to Dictionary.com can simply mean "left-handed." So it was clearly meant to be a left-handed compliment. :) –  jimirings Mar 17 '13 at 4:01

I don't worry about left hand or right hand thread. I remember that the chain always resists tightening the pedal. So I attach the spanner more or less opposite the crank and try to pedal backwards with it (to remove a pedal), or pedal forwards (to tighten a pedal).

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Thanks @moz! Even though this isn't a mnemonic, I like it a lot because it effectively explains why the pedals are threaded this way. –  Zippy May 31 '11 at 11:51
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This is how most shop mechanics remember it as well. Pedal backwards to remove the pedal, regardless of which side of the bike. –  zenbike Jul 23 '11 at 5:27
    
@Zippy, it really is just a handy way to remember it. The real explanation for why the pedals are threaded this way is given in DanielRHick's answer. –  amcnabb Aug 17 '12 at 18:15
    
When putting the bike on its head, things are reversed...remembering that the right side does it "right" and the left side "wrong" makes me remember that the right side is left when the bike is top down. –  TheBlastOne Jul 24 '13 at 4:23

I recently bought a bike and it came with this pedal spanner.

pedal spanner

So I think the easiest thing to do is to write the directions on the spanner!

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Easier still to call the assistance number. –  Daniel R Hicks Dec 8 '12 at 18:01
    
I got a similar spanner from Evans Cycles, my advice was going to be to write it on too! –  DWGKNZ Mar 16 '13 at 20:15
    
Writing it on the tools seems to be the best solution to me. I have tried all of the mnemonics and memory tricks listed here. The problem I always come back to is that one side of the bottom bracket is reverse threaded as well. I can never remember what applies to the bottom bracket and what applies to the pedals. –  jimirings Mar 17 '13 at 4:05

I don't have the wit to convey the knuckle on chain-teeth pain that happens when taking old pedals out, however, how about 'backwards in, forwards out' ?

The thinking being that when you put new pedals in you have to turn the chainset backwards with your trusty 15mm spanner on the pedal and vice-versa for taking old pedals out.

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I just remember it as:

Right Side: Righty tighty lefty loosy

Left Side: Lefty tighty righty loosey

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That confuses me more than helping! :) –  geoffc May 27 '11 at 17:08
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yes it is confusing, but it is fully in line with the way that mechanics think. It is a rule that applies to all threaded interfaces. The only thing you must remember is the exceptions. i.e. gas is backwards. –  Dave May 28 '11 at 19:15

Simple: To figure out which way something is threaded, figure out why it's threaded that way.

The reason for thread directions on rotating objects with lateral load

In general, the thread direction is NOT chosen so that friction from the rotating shaft will tend to tighten things. If that were the case, pedals would be left-hand threaded on the right side and vice-versa.

Rather, it has to do with precession. If you hold a pencil loosely in your left hand while you move the end of the pencil around in a circle with your right hand, the pencil will tend to rotate in a direction opposite of the direction you're rotating the end.

When you pedal a bike forward, the right pedal is moving in a counter-clockwise (or anti-clockwise, on the other side of the pond) direction, relative to the pedal shaft. This produces the counter-intuitive (anti-intuitive on the other side of the pond) effect of driving the pedal shaft in a clockwise direction -- rightie-tightie.

For the same reason, English-threaded bottom bracket cups have a LEFT HAND thread on the right side, and vice-versa. (The sneaky French and Italians just use Loctite and right-hand threads on both sides.)

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This all goes out the window on unicycles where people tend to pedal a lot in both directions, especially when doing trials and other things. You really have to check your pedals before every ride to ensure they haven't come loose. I wonder if fixed gear bikes have some of the same problems? –  Kibbee Jul 23 '11 at 1:19
    
Fixed gear bikes (outside of a circus) aren't ridden backwards enough to be a problem. And with unicycles the direction would be at least 60-80% forward (assuming the seat is asymmetric so the cycle isn't mounted backwards). –  Daniel R Hicks Jul 23 '11 at 11:01
    
I wasn't thinking about riding backwards, but more the backwards force, especially from those who ride without brakes. –  Kibbee Jul 23 '11 at 15:47
    
But it's not the force, but rather the rotation under lateral load that causes precession. You'd get essentially the same torque from precession from a 200 pound guy coasting downhill at 10 mph as from the same guy straining to go uphill at 10 mph, so long as he was putting the same weight on the pedals in both cases. –  Daniel R Hicks Jul 23 '11 at 16:45
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Easy: To remember which way something is threaded, just figure out the effect of the precession. –  Daniel R Hicks Jul 24 '11 at 20:06

Drive side - normal

Non-drive side - opposite.

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Yes! How about: "Right is right and left is wrong"... in the sense that the right pedal works like any bolt/screw tightening to the right or clockwise, while the left pedal works the wrong way round. –  Zippy May 31 '11 at 15:11
    
ok...but drive side can go on either side... –  dotjoe Jun 13 '12 at 21:28

Do you know about the "right hand rule". If you curl the fingers of your right hand in the direction you're turning a screw, the screw moves in the direction of your thumb.

The left hand side of your cranks follows the left hand rule.

And, your wife just asked you why you're curling your fingers and staring at your hand.

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+1 again, not a mnemonic, per se, but I like it! –  Yes I use MUMPS Apr 10 '13 at 23:37

I remember which way to go by turning the pedal wrench toward the back of the bike because to undo the pedal, you have to go backward. To tighten the pedals, turn it toward the front because once you have the pedals on, you can go forward.

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I always figure that when the bolt breaks you were probably turning it in the wrong direction. –  Daniel R Hicks Jul 22 '11 at 21:12
    
@Daniel at that point you're swearing at yourself because you've already stripped the threads trying to pull your cranks off, and it only got worse when you tried to fix that with a tap. Time to get a new bike! –  thajigisup Jul 22 '11 at 21:19
    
I could go into a long-winded discussion about how most people misunderstand the reason for threading left or right on a shaft, but it's late and I'm kinda tired. –  Daniel R Hicks Jul 22 '11 at 21:24
    
@Daniel Doesn't it have something to do with pedaling direction and that you're pedaling forward, so you want the pedals to tighten forward and not loosen from friction? –  thajigisup Jul 22 '11 at 21:27
    
and if you're really in MN, it's not even 5pm. If I am mistaken about the threading, I'd like to know. –  thajigisup Jul 22 '11 at 21:29

Recently I found my own approach:

I approach my bicycle from back, put on an wrench/hex key pointing to back and push it down, if needed, with my foot.

I used to do this with my bike upside down, but ended up with some scratches on my hands from drivetrain.

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To tighten, Rotate any of the pedal same direction of the WHEEL's ROTATION if it were to motion FORWARD.

EASY huh.

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Stay on the drive side of the bike and reach over to remove the non-drive-side pedal. Keep the bike upright. In this case, you turn your pedal wrench towards the back of the bike when removing both pedals and you turn it towards the front when installing them. Lead in with taking off the drive side pedal, and then reach over and do the same motion for the non-drive-side. You won't screw it up.

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The simplest is to look for the "L" and "R" on the respective pedals. Most pedals have them.

If there's no indicator which pedal is left and right, then do a little guess-and-check. If the pedal doesn't start to thread onto the crank after about 1.5 turns then try the other pedal.

Just remember not to force the threads on. They should start easily, and once started should take little force to fully thread. Putting a little grease on the threads is highly recommended, it will prevent corrosion and keep them from ceasing--and provided you snug the threads into the crank there's no extra chance of them coming out.

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A simple way to never be in doubt is just put the crankarm with the pedal you want to remove in the forward position (3 o clock), attach the wrench, and pull up towards yourself. You can even put your foot on the pedal while doing this if it is hard to remove.

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In the organisation where I worked, it wasn't a case of the right hand not knowing what the left hand was doing; the right hand often didn't know what the RIGHT hand was doing.

In the case of bicycle pedals, the right foot knows that the right-hand thread is good.

Thanks for the other suggestions, and simply for letting me find out which way they go (I worked in a bicycle shop 50 years ago, shame on me.

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I think I'm just more confused now. :) –  amcnabb Jul 26 '13 at 17:38

To tighten, turn the way the wheels turn when you're moving forwards.

To loosen, turn the way the wheels turn when you're moving backwards.

This works for both 15mm spanners and the assorted hex down the spindle designs you see these days, with no confusion possible.)

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I was changing some pedals over today and I noticed that (from the top/12 o'clock) the spanner needs to go towards the rear wheel to loosen and towards the front wheel to tighten.

It helped me more than "clockwise" because I was inserting the allen key into the back of the pedal so it was all backwards if you were thinking about "clockwise", etc.

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I'm pretty sure that "righty tighty, lefty loosey" is the official answer, but I do like the "right is right, and left is wrong" one. Makes more sense to me. It's amazing how I can remember some pretty complicated sequences of stuff about all kinds of things, but this simple concept escapes me every time.

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The direction you are pedaling forward always tightens the pedal threads into the crank, it is by design.

Move the wrench in the direction of pedaling forward to tighten the pedal.

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Ambiguous at best. If you put a wrench on a pedal, hold the wrench horizontal, and pedal forward, the pedal will unscrew. –  Daniel R Hicks Jul 26 '13 at 21:20

How about "Back off Jack" This works when the bike is upright.

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I remember:

Right is Right, or

Might is Right (being the drive side).

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To loosen: Bike upright. (like normal)
Wrench on from the top (which is normal - why would I try put a wrench on a pedal from the bottom when its upright??), pull back. "Back off Jack" By far the easiest way to remember. (3 steps, 2 are obvious, just remember "Back off Jack")

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Someone else also suggested this in one of the other answers, but I don't understand why Back off jack would help you remember it. Or, why you need a mnemonic at all, really... –  Batman Jan 30 at 9:42
    
It's kinda like "Fall forward, spring back." –  Daniel R Hicks Jan 30 at 12:51

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