Will an 11 speed mountain cassette (like the CS-M8000) have the same indexing as an 11 speed shimano 105 derailleur and shifter?
I know the cassette needs a spacer to fit on an 11 speed road hub, which has me concerned that road cassettes are overall wider and the shifter will be expecting cogs further apart.
I'm planning to get a derailleur hanger extender to handle the larger cogs, so that's not the aspect of fit that I'm worried about.

1 Answer 1


Yes, it does have the same spacing, and with the 1.85mm spacer it will align perfectly on an 11-speed road hub.

  • I (and many others) have been successful at using what you are attempting to do. I have run an 11-40 CS-M8000 cassette on my gravel bike. Needed to use a SGS-caged MTB rear derailleur to get the additional capacity needed using a Wolfstooth Tanpan cable pull adapter to allow use of Ultegra 11-speed shifters (brifters) with this rear derailleur. Spacing between cogs on the 11-speed MTB cassette is identical to an 11-speed road cassette.
    – Ted Hohl
    Commented Sep 8, 2023 at 3:53
  • 1
    Awesome, thanks!
    – kag0
    Commented Sep 11, 2023 at 18:01

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