Author Topic: Selected Shimano cranks unbonding  (Read 1360 times)


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Selected Shimano cranks unbonding
« on: May 26, 2021, 06:22:31 PM »
Hi All!

If you have one, time to check: This last year has seen a rash of Shimano Hollowtech road cranks unbonding with occasional crankarm fractures following. The drive side crankarms are made in two pieces -- a forged inner that carries the chainrings and a formed thin aluminum outer plate that is bonded to the back plate. These can separate over time and cause...problems.

For more (and to inspect/check your own), see:
Root Google search link:


Possible home repair (though Shimano should warranty/RMA these through their dealers):

Gallery on Instagram:




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Re: Selected Shimano cranks unbonding
« Reply #1 on: May 26, 2021, 08:37:05 PM »
Hi Dan - thank you for that. Just checked and my gravel bike, with Shimano GRX, has these cranks. So not just road cranks!


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Re: Selected Shimano cranks unbonding
« Reply #2 on: May 27, 2021, 08:39:37 AM »
I think it should be pointed out that it seems the cranks that fail are Ultegra. Occasionally Dura Ace but no other model appears to be affected in such a way/volume?
« Last Edit: May 27, 2021, 08:41:31 AM by leftpoole »