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Quick question on replacing stripped Crank Arm

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Quick question on replacing stripped Crank Arm

Old 08-26-15, 03:52 AM
  #1  
wagonfanatic
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Quick question on replacing stripped Crank Arm

I have a Bike Friday New World Tourist that I managed to strip the inner threads of the crank arm (to the pedal). The pedal somehow got lose, and I didn't tighten it soon enough while riding, so it stripped the crank arm threads. Thus I need to just replace the Left Crank Arm (not the whole crank).

The exact specs on the crank are "175mm 30/42/52 130/74 bcd 119mm axle ."

So should any 175mm crank arm work as a replacement?

I was looking at this one on ebay

Sunlite Cycling Alloy Left Arm Crankarm 175 Silver for Bicycling Bike | eBay
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Old 08-26-15, 04:41 AM
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There no way to know if it will fit without trying it. The non-drive side crank arm may be straight, or bent outward or bent inward by the manufacturer. The safest way to find a crankarm that will fit would be to take the bad arm to stores and compare the bent arm to whatever the store has in stock, or something with the manufacturer's name and model number/name on the display crankarm to see if you can find one that is shape similar to your bad one.
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Old 08-26-15, 04:57 AM
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See if your local shop can put a helicoil insert in the crank arm to repair it.
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Old 08-26-15, 05:17 AM
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Okay, great suggestions both. I'll start with the Helicoil insert and move to a full replacement if that doesn't work. I imagine that if I contact Bike Friday they would have the exact replacement arm (although probably at a bit of a premium).

Thanks for the suggestions
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Old 08-26-15, 06:04 AM
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Originally Posted by dsaul View Post
See if your local shop can put a helicoil insert in the crank arm to repair it.
+1 the repaired threads will be stronger than the original
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Old 08-26-15, 09:18 AM
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You could also buy a cheap used replacement on eBay that might not match the other side exactly aesthetically, but will work fine. Just make sure the length is 175mm, like the other one.
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Old 08-26-15, 10:00 AM
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The one sunlite crank arm likely won't work the FSA crank speced on the Friday bikes has a bend offset this crank arm is strait. Bikewagan does have basically the whole crank set to match the OP's in silver for $35 listed on Ebay. If you want just the arm it is probably best to take it to a better stocked shop or bike coop to see if they can find a match. Or as others have said possible fix the threads.

FSA Tempo Triple Road Bike Crankset 175mm 52 42 30 Silver 175 Cranks | eBay

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Old 08-26-15, 10:05 AM
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+2 on the Helicoil; eliminates all the problems of trying to match up the crank arm.

Don't forget to bring in the pedal, too...
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Old 08-26-15, 10:23 AM
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The exact specs on the crank are "175mm 30/42/52 130/74 bcd 119mm axle ."
To be more thorough, that's partial specs you left off the manufacturer, brand and model. and BB type, axle taper style.


Another JIS taper Left arm of the same 175mm length is certainly available Via your LBS.

You have a favorite Bike Shop? You can also ask there about the threaded insert repair job.

Last edited by fietsbob; 08-26-15 at 10:30 AM.
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Old 08-26-15, 03:18 PM
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If you buy a replacement arm you need to ensure that the taper is oriented the same as the old one. Either a corner or a side of the tapered opening will face the pedal, you need to match this.
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