Bent steel pedal arm
 

My "James" cycle has a bent pedal arm and am asking what the best (safest) way of bending it back into place would be. Its slightly bent but enough to just make contact with the chaingaurd while pedaling. I checked the chaingaurd and its fine. I've seen the LBS use a long steel pipe to bend them back in place, is this "the norm?" or do you guys have a better way? Please let me know. :)

I'm not sure what a pedal arm is. Are you talking about the crank arm?

Yes, slipping a long pipe over it is a good first attempt.

Yup, the crank arm.

I think that's fine to do, so long as it's steel. Alloy is another story, of course.

PS. I still want that bike... Not jealous, just envious. ;)

:)

If you do intend to straighten the arm, might I suggest that you remove the crank from the bicycle, first. You would not want the excessive pressure finding a way into the frame set.

For what it is worth, I am working on a Peugeot with a seriously bent steel crank arm. I intend to try to replace it but, being a Peugeot five speed, I might have a tough time finding the perfect crank. If that is the case, I will straighten the arm out using the cold set method. If it looks good when done, I will be set...
http://www.bikeforums.net/attachment...7&d=1304272840

You will notice that the crank arm was bent far enough in to actually damage the lovely original alloy Peugeot fender. How did it get bent so badly? Incredibly poor shipping technique...
http://www.bikeforums.net/attachment...1&d=1304244103




So far, I have collected everything I need to restore the bike, except the correct crank arm. And that might not even be a problem. There just might be one hiding in The Old Shed.

@ Randyjawa, Sweet find! Hope things go well with that crank arm! :twitchy: OK, I remove the crank arm to cold set it, how/what do I anchor the arm to to keep it still and secure enough to bend it with the pipe?

Remove the crank arm and take it to someone with a hydraulic press. You can then have them bend it back right where it needs it. They can control the amount of force needed with the press. Of course, the arm needs to be steel.

Tom

Clamp it in a bench-mounted vise.

The press is the best way. The pipe can work. But before you do. Wrap the heck out of it with electrical tape first to keep the pipe from marring the chrome. If you have a bench vise, that would work also. put it in the jaws with the arc of the bend compressed in the jaws and tighten it down till it mates flat with the jaws and leave it over night. just my 2 cents.

I would heat it and bend in a hydraulic press.

I've had success propping the arm a half inch off the concrete floor and using a maul and a hardwood block. Those arms can be very soft and you can control the bend easily. Or a bench vise and a couple of shims...

Hydrolic press, yeah, I don't know anyone with a hydrolic press.

Vise and pipe works. I did one not too long ago. First measure how far it needs to be bent and do it a littie at a time. You don't want to go past the amount you need because metal fatigues quickly in its "plastic" zone.

Hmmmm, this sounds like a plan! I'm pretty good at whackin' stuff with a hammer! LOL! Think a hard rubber mallet might do the job? I've got one of those.

Use the vise and blocks, as clubman suggests. That is exactly what I intend to do and I know I will get the arm straight.

Do not use heat. Do not use impact. Use a vise, three hardwood or alloy blocks, and press the arm straight. That is what I intend to do and I have done it before, but only with steel. Do not use a bent alloy arm!

I agree with this method. Used it more than once. Wood block and a BFH. If aluminum, you only have very few shots to get it right. Bang on it too much and it will work harden and break, or at least develop cracks which will eventually lead to catastrophic failure at the worst possible moment. Steel, you can beat on all day long.

Clamp it in a bench-mounted vise, preferably with the bench bolted securely to the floor. Slip a long steel pipe over the arm and apply Great Force to move it where it needs to be.

This thread is two years old, that bike id loooong gone.