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Old 06-18-09, 04:46 PM   #1
Sdlong92
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Bent Crank Arm. Must I Replace?

Hello,

My crank arm is bent and I was wondering if there's anything I can do to bend it back? I really don't have the money to buy a set or the tools to do replace them myself if I had the part . Does anyone have any advice on how to bend the drive side arm back into line so this bike is ride-able? It's a slight bend but I can feel it every turn.





Thanks,
Donny
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Old 06-18-09, 04:51 PM   #2
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"Slight"?
Ghetto method is leverage. Like a 12" adjustable wrench with a pipe slid over it to give you a long handle to pull.
You might want to try a new pedal first though, since it appears to be more badly bent than the arm is.
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Old 06-18-09, 04:55 PM   #3
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"Slight"?
Ghetto method is leverage. Like a 12" adjustable wrench with a pipe slid over it to give you a long handle to pull.
You might want to try a new pedal first though, since it appears to be more badly bent than the arm is.
It is pretty slight I feel, I may just try using leverage and bending that sucker back. It's incredibly thick though I'm afraid the frame will get dented if I put too much pressure on it. I think I will thy that new pedal idea first.

Thanks for the input,
Donny
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Old 06-18-09, 04:59 PM   #4
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With a long enough lever you can bend anything. Maybe instead of a wrench you can find a longer pipe that will fit around the arm, reducing the chance of slipping and landing on your wife's minivan.
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Old 06-18-09, 05:00 PM   #5
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That sucks. It could be just the pedal but it looks as though you have a bent crank. Honestly unless you are a super awesome mega beast you will not be able to bend this back to true. Crank arms are designed to take repeated lateral torque of riders standing for hill climbs and whotnot. If you bent the actual crank you are better off just getting a new one. find a used bike shop in your town and get a new crank for about 20 bucks. most of these types of shops will remove your old crank and put the new one on for you for a couple bucks. THey may however charge you more if they have to adjust the front mech for different size chain rings.

BTW a BB tool only costs about $7-10 bucks and you only need a metric ratchet set to put the new one on. Maybe a hex wrench to keep the chainrings if the replacement crank doesn't have em.
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Old 06-18-09, 05:12 PM   #6
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Update: Just tried replacing the pedal and it is slightly better. Rides much better, although I would not ride it as is personally. I guess I'll have to try bending the arm with a pipe, luckily I am a 158lbs beast .

If this fails it will have been one of the worse days in recent memory. I started off the day flying into a crosswalk pole and gouging out a 1/4" diameter hole in my leg I knew I shouldn't have ridden to the gym this morning.

Last edited by Sdlong92; 06-18-09 at 05:26 PM. Reason: Grammar gone nuts!
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Old 06-18-09, 05:43 PM   #7
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"Better"? You mean it's actually ridable? From the pics it looks like it would hit the chain.

Heck if it's ridable, then ride it. And save your shekels.
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Old 06-18-09, 05:51 PM   #8
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I'm afraid the frame will get dented if I put too much pressure on it.
Don't use the frame as leverage. Isolate just the crank itself when applying pressure.
If possible, remove it and put it in a vice.
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Old 06-18-09, 06:51 PM   #9
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Woohoo, check it out. Not too shabby, rides really well now. Not show room floor well, but definitely can't tell anymore! Had trouble with getting enough leverage, I didn't have anything long enough to do the job. So I decided to introduce crank arm to Mr. Mallet, my mallet .






Thanks for the help everyone,
Donny
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Old 06-18-09, 08:05 PM   #10
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Is that a steel crank arm? you haven't broken the end off of it yet, which makes me think steel. But if it's aluminum, I'd feel pretty confident you're going to be riding along and the end of your crank will break off some time soon...

(had a pair of Aluminum handlebars that I bent just a little bit, one handlebar broke off without warning while going over a bump. Luckily, I didn't crash. Now I know not to bend aluminum parts, ever.)
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