Bicycle Mechanics - pedal lever came loose!

This morning on the way in, I discovered my pedal arm/lever (not sure what the official term is - the bit that connects the actual pedal with the cranking bit. er.) had come loose, or more accurately, the nut that fastens it onto the crank had come loose. I managed to tighten it a little with needlenose pliers I had (gotta buy the correct socket later), but it kept coming loose. My question is: how/why did it come loose in the first place? the bike is about 2 months old, so could this have been a manufacturing thing, that it just was never tightened properly? or do I have to worry about self-loosening nuts as long as I cycle?

[SIZE=1]self-loosening nuts? sounds related to a wet dream or something :D

Are you saying the pedal started to unthread itself from the crankarm?

If that is what you mean, I would suspect it was not tight enough to begin with. Normaly alot of torque is used to tighten those things down.

I had a crank arm nut on my Raleigh that came loose 3-4 times. Did not seem to matter is I torgued the heck out of it. But a drop of "locktite" did the trick. Has now been on there for 2+ years without a problem.

Good luck!

Well, it's obvious that the person who assembled it didn't do a good job. If you bought it at a bike shop, bring it back, and tell them to make sure every @&$*ing nut and bolt is properly secure.

If you bought it from a mass-retailer......well, you got what you paid for....

If you bought it from a mass-retailer......well, you got what you paid for....Absolutely right...!

Anyway, if the crankbolts are torqued down correctly, there's no need for loctite as others have suggested.

Crank bolts for square taper bottom brackets run about 325 in-lbs of torque. Sounds like it wasn't torqued enough. Plus, the loctite helps as well.

L8R

Someone may have also put grease on the spindle of the bottom bracket. Chack that out.

If you are using a squar tapper BB and you road it while the crank arm was loose you may want to inspect the arm to see if the square hole has rounded out. even the slightest bit will cause it to keep coming loose no matter how much loctite you use.


the bit that connects the actual pedal with the cranking bit. er.) had come loose, or more accurately, the nut that fastens it onto the crank had come loose

Do you actually have a nut holding your pedals on the cranks?

This statement leads me to think you may be talking about the pedal and not the crank arm/BB bolt. If this is the case then I would seriously susspect the person who built the bike. You do not need to crank down (no pun here) when installing the pedals. They are designed to be tightend in the same direction as if you were pedaling so if anything they would be on tighter.

:beer:

Thanks for the replies!

Follow-up: I bought a socket for it yesterday, and no matter how much I tightened it, within a block or two it was loose again - sounds like oldillini's problem.
And I just don't GET that, because as dirtbikedude said, the nut tightens in the direction the pedals go. Weird.
I'm also a bit worried about the square in the arm having rounded a bit.

I suspect it's a matter of it not being torqued enough on manufacture, and it'll be returning to the shop today for adjustment. Failing that, Loctite it'll be ;)

Thanks for the tips and help though, most useful.

Locktite on a crank???!!!

OK, Einstein, how are you supposed to remove it at a later date?

That has to be the stupidest thing I've read here yet.....

Someone may have also put grease on the spindle of the bottom bracket. Chack that out. I always put grease on the spindle and on crank bolts....... & never, ever had a problem as long as they're torqued down properly...

Never underestimate the value of loctite. Just remember it comes in different flavors:

blue - make things stay where you put them
red - never ever to be removed again

(or was that the other way around?)

However, loctite should not be required on an undamaged crank (I use grease) or undamaged pedal threads.

Hi all - ok so I eventually got it back from the shop, and they fixed it by replacing the pedal crank (the first time I took it in their solution was to tighten it :rolleyes: came loose the next day). my guess is that this will be a recurring problem now, because if there's any damage or wearing on the shaft itself, it'll cause the crank to go too.

Anyway, my question is this: I've been pondering the problem, and I'm now wondering if the initial problem was not caused by me - with poor pedaling technique? if my foot wasn't pushing down like it should, and a slight sideway force was being exerted, wouldn't that screw the crank like mine was? do I need to correct my form?

The best bet imho is that the bike shop or manufacturer screwed up. The way a pedal is screwed on to the crank if anything should tighten it while pedaling not loosen it.

Nope. They are designed to take slight sideways movements.

I don't think anyone pedals without exerting some lateral force (it's why some pedals have float built in)

Blue thread sealer will help, and is removable.

Never grease a square tapered crank axle.

if you used a socket then it's your crank ARM. if you used an open end wrench it's your pedal.

but maybe you used a socket with an allen wrench on the backside of your pedal.


I've had pedals come loose even after I used grease on the threads and ALL my strength on the wrench.

you didn't mention what brand you had, even though sometimes it doesn't matter. but lower end parts often don't have the same quality of threads. or the thread pattern is just off ever so slightly. so they don't match up.

My guess is that this will be a recurring problem now, because if there's any damage or wearing on the shaft itself, it'll cause the crank to go too.

So true, better get them to replace the bottom bracket also before you have to replace the crank arm again.


Anyway, my question is this: I've been pondering the problem, and I'm now wondering if the initial problem was not caused by me - with poor pedaling technique? if my foot wasn't pushing down like it should, and a slight sideway force was being exerted, wouldn't that screw the crank like mine was? do I need to correct my form?

No way. You are not to blame (unless you applied a rench or socket to loosen the bolt).