What's the Difference Between Shimano and SRAM Freehub Bodies?

Shimano and SRAM mountain bike cassettes use different freehub body splines, so a cassette built for one brand's standard will not seat on a hub fitted with the other. Shimano cassettes run on HG for 8 to 11-speed groupsets or Microspline for 12-speed Hyperglide+ groupsets. SRAM cassettes run on XD for 1x mountain bike setups, including Eagle Transmission (T-Type) groupsets, or XDR for SRAM's road and gravel groupsets. Before buying a hub, wheel, or cassette for an Australian MTB build, confirm which of these four standards your groupset needs and which one your hub's freehub body, such as a Hope Technology Pro 5 or Pro 4, is built to.