Freehub Types, Standards, and Compatibility for Road and MTB Wheels

Posted at: Mar 22, 2023

A summary of the different types and standards of freehubs used in road and MTB wheels, along with their compatibility with various cassettes.

Editorial Note: We earn a commission from partner links on cyclabo. Commissions do not affect our editors' opinions or evaluations.

Sponsored Link

Shimano

Shimano currently offers five types of freehub bodies:

  1. Micro Spline (MTB, 12-speed)
  2. HG Spline L2 (Road, 12-speed)
  3. HG Spline L (Road, 8–12-speed)
  4. HG Spline M (Road, 8–10-speed / some 11-speed; MTB, 8–11-speed)
  5. HG Spline S (Cassette-type 7-speed)

On the sprocket side, compatible models are generally designed to match the corresponding freehub. However, there are some exceptions with 10-speed and above, so be careful when installing.

Sprocket / Freehub Body Micro Spline HG Spline L2 HG Spline L HG Spline M HG Spline S
MS 12-speed Sprocket - - - -
HG-L2 12-speed Sprocket - - -
HG-L 11-speed Sprocket - - - -
HG-M 11-speed Sprocket - -
with 1.85mm spacer
-
HG-M 10-speed Sprocket - -
with 1.85mm spacer
-
HG-M Old Road 10-speed Sprocket - -
with 1mm + 1.85mm spacers

with 1.0mm spacer
-
HG-M 9-speed Sprocket - -
with 1.85mm spacer
-
HG-M 8-speed Sprocket - -
with 1.85mm spacer
-
HG-S 7-speed Sprocket - - - -

For a detailed explanation of Shimano’s freehub bodies and sprockets, see the article below:

SRAM

SRAM initially released only sprockets compatible with Shimano’s HG spline standard, but introduced its own standards when moving to 12-speed systems.

However, considering users of traditional HG spline wheels, SRAM continues to offer 12-speed sprockets compatible with HG spline in addition to its proprietary XD and XDR driver systems.

XD Driver

When SRAM moved to 11-speed systems, it introduced its proprietary freehub standard: the XD Driver. While older SRAM sprockets were compatible with Shimano HG spline, XD Driver sprockets have a completely different shape and mechanism.

One of the defining features of the XD Driver is support for a minimum top gear of 9T. This was developed in response to the needs of the MTB scene, where wide-range cassettes became essential due to the growing popularity of 1x (single front chainring) setups.

However, a downside is the limited number of complete wheelsets available with XD Drivers. Once locked into this SRAM-specific standard, upgrade options can become quite limited.

XDR Driver

The XDR Driver is a road-oriented version of the XD Driver, extended by 1.85mm. Since both are SRAM standards, an XD sprocket can be mounted on an XDR driver using a 1.85mm spacer. However, due to the shorter length, XDR sprockets cannot be used on XD drivers.

Although it’s a road-specific standard, it has become increasingly common on gravel bikes equipped with SRAM components.

Campagnolo

Campagnolo uses a proprietary freehub body standard, often referred to as the “Campy Freehub.”

Known for its uniquely designed ergonomic shifters, Campagnolo has seen a decline in road bike market share in recent years. As a road-specific component brand, its Campy Freehub is about as rare as SRAM’s XD driver in today’s market.

Freehub Compatibility

Freehub / Sprocket HG Spline M HG Spline L XD Driver XDR Driver Campagnolo
HG Spline M - - - -
HG Spline L
(with 1.85mm spacer)
- - -
XD Driver - - - -
XDR Driver - -
(with 1.85mm spacer)
-
Campagnolo - - - -

Sponsored Link

Learn more about sprockets

Learn more about bicycle groupset

Mechanics New Posts