With the Shimano XTR the Japanese launched their first 11-speed drivetrain on the market. As the focus during development was on a fine gear gradation, the XTR cassette was left at a maximum of 40 teeth. Some bikers wanted a little more range in 1x mode with a chainring at the front. Reader Peter A. would like to ride a 10-42 Sram cassette with a Shimano XTR rear derailleur and asks: "Can a rear derailleur that usually works with an 11-40 11-speed cassette also be combined with a Sram 11-speed cassette? Is the capacity of the rear derailleur sufficient up to 42 teeth?"
Michael Wild from Shimano says quite clearly:
"From our point of view, mixing Shimano and Sram always means no. In this case, however, this is also directly due to the specifications of the rear derailleur: With the Shimano 11-speed rear derailleurs for mountain bikes, the smallest sprocket must have no more and no less than eleven teeth. However, the XTR rear derailleurs have capacities that work with 42-tooth cassettes (2x) or 46-tooth cassettes (1x only) of the XT. With 3x, the SGS rear derailleur must be used (then only up to 40 teeth)."
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