Wondering if somebody could shed some light - I need to replace a left crank arm due to damage. My chainset is 105 5800 170mm and looking through ebay there are a few ultegra 6800 170mm left hand cranks available. Will these fit? Thanks in advance

[image] shafwaan: Wondering if somebody could shed some light - I need to replace a left crank arm due to damage. My chainset is 105 5800 170mm and looking through ebay there are a few ultegra 6800 170mm left hand cranks available. Yes, they’ll work fine as both are (afaik) 11-speed setups fr…

Thanks for the advice, much appreciated!

Every generation of HollowTech crank arms are cross-compatible as the splines haven’t changed, to the best of my knowledge. The left arm isn’t exactly what you’d describe as ‘speed specific’. Mike

[image] themagicspanner: Every generation of HollowTech crank arms are cross-compatible as the splines haven’t changed, to the best of my knowledge. The left arm isn’t exactly what you’d describe as ‘speed specific’. My bad. I read this too quickly. I thought he was going to take this opportu…

Re-cycling this thread: My big Chain ring is worn and needs to be replaced. It’s a 105 5800 chainring and crank arm. Would an Ultegra chainring fit?

6800 would. Not R8000, as it is a 4 bolt pattern versus the 5 bolts of 5800/6800.

5800/ 6800 are 4 bolt as well, but won’t fit bc the inner chainring on r8000 series moved inboard ever so slightly.

Ultegra and 105 compatibility

Equipment

markryd September 25, 2020, 5:32am 13

Yes. And I’ve done exactly this, fitted an 6800 large chainring to a 5800 crankset.

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Ultegra and 105 compatibility

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