Depends

Will a Shimano 11-speed road cassette fit on a 10-speed body?

It depends on the model. Standard ROAD 11-speed cassettes (105/Ultegra/Dura-Ace) require the wider HG Road body (~36.75 mm) and will NOT fit on an 8/9/10-speed body (~34.9 mm). The exceptions are the wide-range CS-HG700-11 and CS-HG800-11 (11-32/11-34), built at the 10-speed width: they mount on a 10-speed/HG-M body without a spacer. Note: the 1.85 mm spacer is for the opposite direction (a narrow cassette on a wide Road body), not to make a wide cassette fit a narrow body.

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What you need — before you buy

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