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I'm looking at getting a left side crank power meter and was wondering would the various shimano left cranks available with power meters fit with the existing Ultegra 6800 crankset I have? The 105 or even dura ace. Thanks

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  • We have quite a few similar questions. The answer is the same, the left crank is independent and the interface universal (among Hollowtech || cranksetes), you can mix various left crsnks freely. – Vladimir F Nov 1 '20 at 23:30
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    This one has 105 and Ultegra bicycles.stackexchange.com/questions/60274/… Another similar, but there are more bicycles.stackexchange.com/questions/24798/… – Vladimir F Nov 1 '20 at 23:31
  • Is the Q-factor any different between models and generations? I would expect Shimano to have slightly tweaked the Q-factors (perhaps narrower for race-oriented DA etc) – MaplePanda Nov 2 '20 at 0:27
  • @MaplePanda IIRC, the reported Q-factor and chainline should be identical among the road Hollowtech II cranksets. GRX (gravel groupset) have 2.5mm wider chainline, and slightly wider Q-factor also. – Weiwen Ng Nov 2 '20 at 3:20
  • @WeiwenNg the GRX chainsets are 3.4mm wider chainline, according to the Shimano specs. However the FD is 2.5m wider. No idea why. Q-Factor is 5mm more. – thelawnet Nov 2 '20 at 11:04
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Yes, you can use the left crank arm of your choice from the Hollowtech II road series. (105, Ultegra, DA)

It is quite commonly done, especially using a newer generation arm on an older chainset where the older style is no longer available.

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  • Yeah, you can mix+match according to the Shimano compatibility chart. The 11s Ultegra + 105 left cranks are hollow forged whereas only the 105 drive side crank is hollow forged. Bonded cranks have a history of cracking+breaking. So I use a Frankenstein Ultegra left side + Stages power meter, 105 drive side and Dura Ace rings. – Olsonist Apr 1 at 15:31
  • I have never seen these bonded cranks break. What kind of animal are you @Olsonist ? – JoeK Apr 1 at 19:50
  • A worried Clydesdale. bikeradar.com/features/shimano-crank-failure – Olsonist Apr 1 at 22:18
  • I'd hardly call that a worry especially in the context of Shimano replacing it even out of warranty plus was clearly damaged for some time before obvious failure. Don't live your life in fear. – JoeK Apr 2 at 16:31

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