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I must have crossed threads like an idiot when I installed pedals for my new SPD cleats. After several miles of riding (~100-200 m), I suddenly got this inexplicable rolly, bumpy motion in my foot. The pedal looked skewed out of the crank arm. I removed it with my pedal wrench. Out came several rings of crank thread material. The pedal is fine.

The previous pedals that I removed were aluminum platforms and needed a dousing of degreaser and hot water to come unstuck.

I could probably screw the pedal back in with the remaining thread in the crank arm. Is this downright stupid to do?

EDIT: Some pictures and specs for further review

The pedal is a standard SPD Shimano road. I don't have the specific model number, I lost the box. The Pedal

The crankset is an Omega FS6. It came prepackaged with my bike which was a rebuild. The former aluminum pedals were locked in there like a nightmare. The bike mechanic used thread sealant. Once I wrenched them off, I tried my best to clear out any offending sealant that remained in the threads. The Crank

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Pictures please. They might be fine. How much and what kind of riding? What cranks and peddels? –  alex Mar 6 '13 at 17:32
    
Added pics. My riding is pretty casual, not more than 6-10 miles at a time for commute and a half century every other weekend. –  ashkan Mar 6 '13 at 21:08
    
Is is possible that you got the left and right peddles crossed? (Even with gunk in the threads, the pedals should have screwed in with only mild force.) –  Daniel R Hicks Mar 7 '13 at 2:25
    
There is a slight possibility that your cranks have a different thread. I think Sheldon has an article on that -- some French or Italian "standard" that is close to the usual standard but not quite. –  Daniel R Hicks Mar 7 '13 at 13:03
    
Pics are good, the consensus seems to be that your cranks are toast. When you get new cranks, be sure to grease the threads on the pedals and make sure you thread them on in the proper direction (non-drive side is reverse threaded). Don't force it. –  Benzo Mar 7 '13 at 13:27
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4 Answers 4

Short answer, yes, you need to replace. You can try heli-coil, but I wouldn't for this application.

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Your cranks are pretty much toast, and even if you try to fix them, you'll always be suspicious of them and won't be able to ride hard without worry.

Toss them in the trash and get new ones, and be more thorough when reinstalling your pedals.

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I foolishly did something similar and rode on just loose enough pedals long enough that they started orbiting and carved a nice wedge right out of the crank, destroying them.

I suspect that is where you might be headed here. Get new cranks. Alas.

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I've done something like that ages ago. But had a friend working in CNC shop - he made a steel insert to fix the threads. And 10 years after - the cranks are still going fine. But not everyone have access to CNC machinery. So it might be easier and cheaper to replace the cranks.

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