Pedal Unscrewing
09-01-07, 02:52 PM
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Pedal Unscrewing
Having a strange problem and was wondering if anyone had any insight. My right side pedal seems to like to unscrew itself. I'd check it every now and again and it'd be screwed halfway out of the crank. I'd tighten it back down and a few days later, same thing. A week ago I borrowed a nice long pedal wrench and really cranked it down hard. Seemed to be OK, but I went on a long ride today, checking it periodically, and halfway up a long climb it screwed itself completely out of the crank. Took the last few threads with it too. It was still tight when I checked it about 5 miles previously. So, now I get to buy myself a new crank. Yay! Or not. I figure I should figure out what the problem is before it happens again though. For reference, I'm using EggBeater C's with the road cleats (the ones with the little 'pontoons' on the sides). Bearings seems fine, it spins just as freely as it did when new. The bike's fixed, but I just can't see back pressure/skidding unscrewing the pedal. The only thing I can think of is that maybe the inside 'pontoon' on the cleat is rubbing against the spindle body and locking the pedal up. But again, it'd have to be overcoming some seriously tight threads. Anyone ever seen this issue or have any ideas?
09-01-07, 03:13 PM
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09-01-07, 03:30 PM
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this may be a stupid question, but are you missing a washer?
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09-01-07, 03:44 PM
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Hehe... uh oh... I hope I'm not about to appear daft after my previous post. Washer? I wasn't aware there was supposed to be a washer with pedals. The EggBeaters certainly didn't come with one and the installation instructions didn't mention such.
09-01-07, 03:48 PM
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If your crank has a dimple on it, you need to put a pedal washer in it. That's not the problem anyways. Once you have verified that you have put the pedals on with the correct torque and you're still having the problem, then put some low strength loctite on it. I really doubt you need to take the last action, and only as a last resort.
09-02-07, 11:41 AM
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You don't need to replace the crank. The threads can be replaced by your LBS.
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09-02-07, 06:24 PM
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Usually, I don't torque the pedals to gorilla strength. I usually snug it down with a pedal wrench, and probably around 20 ft-lb (just a guess). What's perplexing is why are the pedals unscrewing themselves? If you pedal forwards, that joint is "self tightening".
09-02-07, 08:17 PM
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It's possible that there could be drag in the pedal bearings under load even though the pedals spin freely when they are not not under load. This could happen if the bearings are too loosely adjusted; which, with use, will cause damage to the bearings and races. Is there any end play in the pedal bearings? Your description of the pedal coming out while you were climbing a hill would seem to support the idea that the pedal bearing may not be turning freely under a heavy load. Contrary to a previous post, pedaling forward will tend to unscrew the pedals if there is enough drag in the pedal bearings.
09-02-07, 08:50 PM
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Originally Posted by DMF
You don't need to replace the crank. The threads can be replaced by your LBS.
Originally Posted by MudPie
What's perplexing is why are the pedals unscrewing themselves?
Originally Posted by J.P.
It's possible that there could be drag in the pedal bearings under load even though the pedals spin freely when they are not not under load. This could happen if the bearings are too loosely adjusted; which, with use, will cause damage to the bearings and races. Is there any end play in the pedal bearings? Your description of the pedal coming out while you were climbing a hill would seem to support the idea that the pedal bearing may not be turning freely under a heavy load. Contrary to a previous post, pedaling forward will tend to unscrew the pedals if there is enough drag in the pedal bearings.
09-02-07, 08:50 PM
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Actually... does anyone know if there's someone out there that makes thread repair kits for pedal threads (ala Helicoil)? The Helicoils was 18tpi at 9/16". (I might start a new thread for this one, but I'll start here.)
Last edited by operator; 09-02-07 at 09:48 PM.
09-03-07, 08:03 PM
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[/QUOTE]I'm not 100% sure I know what end play is in relation to bearings, but if I understand it correctly, there is about 1mm of end play in the right pedal, none perceptible in the left. I'm pushing and pulling the pedal as if I were trying to remove it from the spindle. Doesn't seem good, regardless of the type of play I'm describing. These pedals are practically new (less than a month old) and I'm a light rider (120 lbs), so I doubt I've damaged them in the short time I've owned them. Perhaps a candidate for warranty replacement?[/QUOTE]
It sounds like what you are describing is end play. If the bearings are adjusted properly there should be no perceptable end play so it sounds like the right pedal is not properly adjusted. If they are out of adjustment after only one month of riding it's likely that they weren't assembled correctly in the first place. I don't know whether or not the races or bearings could be damaged in one month of riding if they weren't properly adjusted.
It sounds like what you are describing is end play. If the bearings are adjusted properly there should be no perceptable end play so it sounds like the right pedal is not properly adjusted. If they are out of adjustment after only one month of riding it's likely that they weren't assembled correctly in the first place. I don't know whether or not the races or bearings could be damaged in one month of riding if they weren't properly adjusted.
Last edited by J.P.; 09-03-07 at 08:09 PM.
09-03-07, 08:26 PM
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Try a little loctite (blue).
09-03-07, 09:02 PM
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odd, i never put any pressure on pedals, i tighten them with my fingers then give a 1/4 turn with a wrench and ride. pedals are self tightening, due to the threads (left is reverse threaded for a reason) just use some loctite and you should be good
just wondering, can you put crank arms on the wrong side?
just wondering, can you put crank arms on the wrong side?
09-03-07, 09:20 PM
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odd, i never put any pressure on pedals, i tighten them with my fingers then give a 1/4 turn with a wrench and ride. pedals are self tightening, due to the threads (left is reverse threaded for a reason) just use some loctite and you should be good
just wondering, can you put crank arms on the wrong side?
just wondering, can you put crank arms on the wrong side?
09-03-07, 09:30 PM
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Sure you can... https://sheldonbrown.org/gunnar/index.htm
Though I can't imagine what good reason there would be to so. Other than being Sheldon, of course. And there are drawbacks, namely the pedal threads being backwards. So, rather than being self tightening, the pedals will be self loosening. That might be a good reason for using Loctite on pedal threads.
Oh, and despite all the advice to do so, I will most definitely not be Loctiting my pedal.
Though I can't imagine what good reason there would be to so. Other than being Sheldon, of course. And there are drawbacks, namely the pedal threads being backwards. So, rather than being self tightening, the pedals will be self loosening. That might be a good reason for using Loctite on pedal threads.
Oh, and despite all the advice to do so, I will most definitely not be Loctiting my pedal.
09-03-07, 09:40 PM
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is that he problem, crank arms on the wrong side?
and ive had pedals on that i tightened just nice (the 1/4 turn has them snug) they were so tight that i was lucky WD-40 worked. that was after a year
and ive had pedals on that i tightened just nice (the 1/4 turn has them snug) they were so tight that i was lucky WD-40 worked. that was after a year
09-03-07, 09:43 PM
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Originally Posted by norco_rider77
is that he problem, crank arms on the wrong side?
Originally Posted by norco_rider77
and ive had pedals on that i tightened just nice (the 1/4 turn has them snug) they were so tight that i was lucky WD-40 worked. that was after a year
09-03-07, 09:49 PM
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Loctite comes in different strengths, for different applications. The blue loctite I've used is "medium strength," which means you should be able to break it loose with hand tools. It might be strong enough to solve your pedal problem, but definitely not so strong you can't remove the pedals later on. You should degrease the threads before applying loctite. I'd say medium strength loctite wouldn't be a bad idea in your situation, it's certainly not going to hurt anything, and might solve the problem-
09-03-07, 09:56 PM
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my caliper mount things have blue loctite
(that is loctite, isnt it?)
(that is loctite, isnt it?)
09-03-07, 10:01 PM
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Loctite comes in different strengths, for different applications. The blue loctite I've used is "medium strength," which means you should be able to break it loose with hand tools. It might be strong enough to solve your pedal problem, but definitely not so strong you can't remove the pedals later on. You should degrease the threads before applying loctite. I'd say medium strength loctite wouldn't be a bad idea in your situation, it's certainly not going to hurt anything, and might solve the problem-
09-03-07, 10:11 PM
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I wonder if this is related to using back pressure on your fixed gear to slow down. But even so, you must be pedaling forward more often than back pedaling.
Only on the right side? It seems like the left pedal would unscrew, too.
From Sheldon Brown's glossary:
Only on the right side? It seems like the left pedal would unscrew, too.
From Sheldon Brown's glossary:
The right pedal has a normal thread, but the left pedal has a left (reverse) thread.
The reason for this is not obvious: The force from bearing friction would, in fact, tend to unscrew pedals threaded in this manner. The fact is, however, that it is not the bearing friction that makes pedals unscrew themselves, but a phenomenon called "precession".
You can demonstrate this to yourself by performing a simple experiment. Hold a pencil loosely in one fist, and move the end of it in a circle. You will see that the pencil, as it rubs against the inside of your fist, rotates in the opposite direction.
Ignorant people outside the bike industry sometimes make the astonishing discovery that the way it has been done for 100 years is "wrong." "Look at these fools, they go to the trouble of using a left thread on one pedal, then the bozos go and put the left thread on the wrong side! Shows that bicycle designers have no idea what they are doing..."
Another popular theory of armchair engineers is that the threads are done this way so that, if the pedal bearing locks up, the pedal will unscrew itself instead of breaking the rider's ankle.
The left threaded left pedal was not the result of armchair theorizing, it was a solution to a real problem: people's left pedals kept unscrewing! I have read that this was invented by the Wright brothers, but I am not sure of this.
Note! The precession effect doesn't substitute for screwing your pedals in good and tight. It is very important to do so. The threads (like virtually all threads on a bicycle) should be lubricated with grease, or at least with oil.
The reason for this is not obvious: The force from bearing friction would, in fact, tend to unscrew pedals threaded in this manner. The fact is, however, that it is not the bearing friction that makes pedals unscrew themselves, but a phenomenon called "precession".
You can demonstrate this to yourself by performing a simple experiment. Hold a pencil loosely in one fist, and move the end of it in a circle. You will see that the pencil, as it rubs against the inside of your fist, rotates in the opposite direction.
Ignorant people outside the bike industry sometimes make the astonishing discovery that the way it has been done for 100 years is "wrong." "Look at these fools, they go to the trouble of using a left thread on one pedal, then the bozos go and put the left thread on the wrong side! Shows that bicycle designers have no idea what they are doing..."
Another popular theory of armchair engineers is that the threads are done this way so that, if the pedal bearing locks up, the pedal will unscrew itself instead of breaking the rider's ankle.
The left threaded left pedal was not the result of armchair theorizing, it was a solution to a real problem: people's left pedals kept unscrewing! I have read that this was invented by the Wright brothers, but I am not sure of this.
Note! The precession effect doesn't substitute for screwing your pedals in good and tight. It is very important to do so. The threads (like virtually all threads on a bicycle) should be lubricated with grease, or at least with oil.
09-03-07, 10:14 PM
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Sure you can... https://sheldonbrown.org/gunnar/index.htm
Though I can't imagine what good reason there would be to so. Other than being Sheldon, of course. And there are drawbacks, namely the pedal threads being backwards. So, rather than being self tightening, the pedals will be self loosening.
Though I can't imagine what good reason there would be to so. Other than being Sheldon, of course. And there are drawbacks, namely the pedal threads being backwards. So, rather than being self tightening, the pedals will be self loosening.
I don't think the SPDs would work backwards due to the shape of the cleats.
Sheldon "Don' Nee' No Steenkin' Loctite!" Brown
09-03-07, 10:24 PM
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I agree, it might solve the immediate problem of my pedal unscrewing itself. Until the bearings get even worse and drag enough to overcome the Loctite too. Not to mention, I'm not super excited about the idea of pedaling against that drag. They're new pedals, so they're going back. (i.e. "Thanks guys, I've got the answer to my question now")
). Good luck with the pedals-
09-03-07, 10:32 PM
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i never ment to say loctite would be bad, that thought never entered my mind