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Freehub bodies

The freehub body is the splined part your cassette mounts on — it must match your drivetrain. Open one to see which trainers offer it.

Quick answer

Shimano/SRAM 8–11-speed use HG; SRAM 1×12 MTB uses XD; SRAM road uses XDR; Shimano 12-speed MTB uses Micro Spline; Campagnolo uses its own. Direct-drive trainers ship with HG and sell the others separately.

Shimano / SRAM

Shimano/SRAM HG (HyperGlide)

8/9/10/11-speed · min 11T

Shimano

Shimano HG 11-speed road

8/9/10/11-speed · min 11T

SRAM

SRAM XD Driver Body

11/12-speed · min 10T

SRAM

SRAM XDR Driver Body

11/12/13-speed · min 10T

Shimano

Shimano Micro Spline

12-speed · min 10T

Campagnolo

Campagnolo

9/10/11/12-speed · min 11T

Campagnolo

Campagnolo N3W

12/13-speed · min 9T

Zwift

Zwift Cog (virtual shifting)

8/9/10/11/12-speed · min 14T