Crank arm (non drive side) completely stripped at the pedal opening
 

Brand new 105 crank. I rode 20 miles on Friday without a single issue.

Today I get on the bike and start pedaling and the left pedal feels wobbly. Turns out the pedal had stripped every thread on the non drive side crank arm.

Anyone have this happen before? What's been everyones experience with shimano warranty services?

No n+1 either which means no cycling for me until this gets replaced, which is the worst part of the story

Was the pedal installed tightly? By whom ?

This sounds like an installation error, not warranty

What kind of pedals? Who installed the crank?

Both me. The crank is fine. I suspect the pedal came loose and the force caused it to pull away from the threads. I've installed pedals hundreds of times over the years and never had one come loose.

Bummer. Helicoil repair is usually the most cost-effective means of dealing with this.

Aren't pedals by virtue of the threads not supposed to come loose?

I've seen pedals fall off from not being tightened, and more frequently they can creak when they're snug but not tight enough.

The mechanic accidentally crossthreaded the pedal and ruined the crank arm.

Quote:

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Originally Posted by JohnDThompson (Post 14541709)

Bummer. Helicoil repair is usually the most cost-effective means of dealing with this.

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Im going try *****ing at some poor, unsuspecting shimano customer service rep until they replace it for free.

If that fails, any idea how bad shimano is going to **** me for a new crank arm?

This is what I thought as well

Wow. You are person companies HATE dealing with. You installed the pedals loose, and the threading got damaged. It's your fault. What does Shimano have to do with that? As someone who has a clue said above, get a helicoil installed, learn your lesson, and don't harass CSRs because you're a cheapass.

Its worth a shot

Who installs these helicoil inserts btw

I wouldn't bother with that. 105 cranks aren't that much or you could search ebay for the arm only, they pop up on there from time to time.

A helicoil is $15-$20. Good luck getting a NDS arm for that. It's actually an improvement over the original soft aluminum

Just get one side replacement from QBP

do they sell to the public? Looks like a wholesaler, you need a login to browse the catalog

who actually installs these inserts? Bike shops?

I just logged in to my QBP account to see if they are available, and 105 is not.

They do have Ultegra 6600 + 6700 left crankarms.

Your local bike shop can get the non drive side. Assuming that Ultegra and 105 have the same Q factor offset, go with that. If you were to put the helicoil in, I would have a machine shop do that where they can insert it with precision.

The one issue with having a machine shop do the helicoil is that they may not have a left-hand helicoil for the non-drive side arm.

The threads actually are opposite... Pedaling forces would go towards loosening. I presume that is for some good reason but I can't imagine what. Same with BB cups.

For example, on your left pedal, to tighten it, you turn it counterclockwise (looking at it from the left side). However, friction in the bearings would tend to turn the spindle clockwise. Likewise, with drive side BB cup is reverse thread so to tighten it, you turn it counter-clockwise (looking from the right side) and bearing friction would tend to turn it clockwise.

Well, shimano is backordered until the end of august

FML

sounds like it's time for an upgrade. :lol: