Bicycle Mechanics - Crank coming loose

Problem with one of my cranks coming loose.Had them on the bike now for about 3 years and been fine, but one just keeps coming loose.4 year old chorus chainset.Ive took out the bolt and cleaned it, tightened it up again...even put Loctite on it, but after a while still comes loose.The threads seem fine and dont appear to be worn?confused :(

hate to say it, but you might need a new crankset/arm. you see, the problem is not with the bolt itself. it is the taper/crank interface. if you rode with it not torqued correctly, then you may have rounded off the square, and so it gets loose. try torquing the bolt to the reccomend torque. Check the park site or campy's site for the proper torque values.

Problem with one of my cranks coming loose.Had them on the bike now for about 3 years and been fine, but one just keeps coming loose.4 year old chorus chainset.Ive took out the bolt and cleaned it, tightened it up again...even put Loctite on it, but after a while still comes loose.The threads seem fine and dont appear to be worn?confused :(

My bet is that your crank arm spindle hole has been hosed. Once they come loose, the hard bottom bracket spindle wallows out the softer aluminum crankarm and they tend not to want to stay in place after that. That's why I always use a torque wrench when tightening crank arms. My experience has been that many people, when left to their own devices, tend to undertorque crank arms.

I am currently having the same problem with my crankarm. Ever since i had the BB worked on, the crankarm is constantly coming loose. mine is also tapered. After consulting that manuel on that can be accessed on this site and talking with other people i think my tapered crankarm is no long as square as it should be. Is it possible to get another left crankarm, without getting a the whole crankset?

I am currently having the same problem with my crankarm. Ever since i had the BB worked on, the crankarm is constantly coming loose. mine is also tapered. After consulting that manuel on that can be accessed on this site and talking with other people i think my tapered crankarm is no long as square as it should be. Is it possible to get another left crankarm, without getting a the whole crankset?

Yup. That's a fairly common repair part. Any average or better LBS can get you one. Depending on your crankset, it might not match perfectly.

Check out the Branford Bike (http://www.branfordbike.com/crank/crank.html) website. They sell all sorts of Campy parts (including individual crankarms).

SteveE

This is why I only use splined bb's and cranks on my bikes. :D

well, i sent a picture of my crank arm, actually the end that connects to the spindle to a guy on another forum and he said that it didn't look so bad.
these pictures can be found at the following website.... http://community.webshots.com/user/joebob4567

Anyways, i bought a torque wrench today. Maybe now i'll get it right and it will stay on longer (hopefully for good). i also bought some Red loctite, that will really make it stay on :-).
Well my question for today is what is the amount of torque that i should put on the nut that i am tightening that holds on my crankarm? I have a 1993 bianchi ocelot. The crank arm says it is a FC-TY21 Shimano, yet i am still not sure what torque to put on it. So it would be appreciated if you could tell me, if you know. :-)

Thanks.