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Stripping threads on crank arms

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Stripping threads on crank arms

Old 09-25-20, 11:50 AM
  #1  
crankarmbreaker
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Stripping threads on crank arms

True to my name, I just trashed a set of crank arms! They cost $350 to replace. On the previous set, on which I had 4,600 miles, the steel pedals were going bad. That's not a major crisis, but then when I removed said pedals to replace them, it was really, really hard to remove them, and a huge amount of aluminum came off on the threads of the pedals. And then the crank arms were unusable. I have done this to previous cranksets, too over the years, stripping the crank arm threads in a manner the mechanics said they didn't previously think was possible but then this is you, Eric.

To give a little background, I weigh 350 pounds and am 6 feet 9 inches tall. A year and a half ago, I got a new Rodriguez custom frame bike built for me and they put High Sierra 210mm crank arms on it. I called the High Sierra people to order a new set and they did have a pair in stock and then the salesman told me to use anti-seize lubricant, something I'd never heard of. Turns out it's the sort of thing car mechanics use on spark plugs to keep them from bonding to the other metal. So I got some and boy is it gooey and gets on everything. But I put it on the threads of the new pedals and have been riding for a few weeks since then.

Ok, so the question I have for you: Has anyone here stripped the threads off of crank arms this way? And have you found a solution to it?
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Old 09-25-20, 12:17 PM
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No, I still have the same cranks on my 35+ year old bike (but it hardly gets ridden any more). For 10 years it was my only bike and I put about 3000 miles on it annually.
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Old 09-25-20, 12:59 PM
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Old 09-25-20, 03:22 PM
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I haven't stripped the aluminum threads at the pedal interface, probably because I always put plenty of grease on the pedal before I thread it it. Plenty means as much as the threads will hold. If any squeezes out, wipe it off with a paper towel or rag.
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Old 09-28-20, 10:27 AM
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I have broken the threaded insert in a set of Hussefelt downhill cranks on my fatbike. They are now obsolete, so had to replace cranks and bottom bracket to current standards. I have snapped bottom brackets and worn the interface of square taper cranks and bottom brackets. I change pedals regularly, so grease on the threads keeps those from seizing.
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Old 09-29-20, 04:45 PM
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Originally Posted by pdlamb View Post
I haven't stripped the aluminum threads at the pedal interface, probably because I always put plenty of grease on the pedal before I thread it it. Plenty means as much as the threads will hold. If any squeezes out, wipe it off with a paper towel or rag.
+1. I also try to remove them, clean the threads and reinstall once a year or so. And watch the thread direction!
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Old 10-08-20, 12:16 PM
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anti-seize is a good idea. dissimilar metals can corrode and/or cold weld together. be careful using it on torque-critical fasteners though, because it can cause inaccurate or inconsistent torquing.
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Old 12-15-20, 11:56 PM
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I have always used grease on crank arms. I put grease on the pedal threads and on the axle ends before attaching the cranks. I use grease on the bolts that hold the cranks on the axle. I put grease on my aluminum seatposts before putting them in my steel and aluminum frames. I have never had one slip. I grease both quill stems and threadless fork type stems before attaching them to their forks. Never had any of them slip either. Anywhere things bolt together I put on grease as a form of anti-seize. Pay heed though to khyatt's warning about over tightening. It is easy to do with greased bolts.
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Old 12-16-20, 01:26 AM
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I stripped a crank removing a pedal.

A local shop had a tool to rethread the hole and inserted a heli coil to fit the new pedals.

Holding great for the last 6 years.

Like this. Paid about $25 vs replacing an Ultegra crank.

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