Shimano Sprocket and Wheel Compatibility Explained

Key Points for Understanding Compatibility Between Shimano Cassettes and Wheels

If cassette and wheel compatibility were as simple as “always use cassettes that match the exact speed of the wheel,” things would be easy. However, Shimano provides broader compatibility between cassettes and wheels, which benefits users by offering more component choices — though it can make compatibility more complex and confusing.

Still, even though Shimano’s cassette and wheel compatibility may appear complex at first, it’s actually quite simple once you understand these three key points:

1. The type of freehub standard used on the wheel
2. Which freehub standard the cassette is compatible with
3. Differences among some irregular cassettes

Shimano Freehub Standards

Let’s first look at the types of freehub standards Shimano uses to mount cassettes on wheels.

When choosing a wheel, you’ll often see specs saying “Shimano Freehub compatible.” But in fact, there are five different standards under the general label of “Shimano Freehub.”

Freehub and Cassette Spline Compatibility | Shimano

These can be grouped into two categories: HG spline series and Micro Spline. Let’s break them down.

HG Spline Series

The “HG” in HG spline stands for Hyper Glide, Shimano’s shifting technology. HG spline freehubs are also referred to as “Shimano Freehub” or “Shimano HG”.

There are four types of HG spline freehubs, each differing in height and spline count.

Originally, “HG spline M” was used for 8-speed through MTB 11-speed. When Shimano released 11-speed road components, they introduced “HG spline L”, which kept the same spline shape but raised the height by 1.85mm.

Later, “HG spline L2” was introduced for road 12-speed cassettes. It features a taller body and twice the splines (18) for a more secure fit. Despite this, Shimano maintained backward compatibility, so many 12-speed road cassettes still fit older “HG spline L” hubs. This means what was once labeled as “11-speed road wheels” are now effectively “11/12-speed road wheels.”

Also, since “HG spline L” can support 8–10-speed cassettes with a spacer, it offers broad compatibility with nearly all Shimano cassettes — except for those designed specifically for Micro Spline.

Micro Spline Series

The Micro Spline standard was introduced for Shimano’s MTB 12-speed drivetrains. Unlike the “Shimano Freehub” or “Shimano HG,” Micro Spline may also be abbreviated as “Shimano MS.”

Micro Spline hubs have 23 splines, more than the HG series, and a lower body height of 26mm.

This new format supports not only 12-speed MTB cassettes but also allows for a smallest cog size of 10T, which isn’t available in road 12-speed.

Shimano initially announced an 11-speed Micro Spline cassette called “CS-M9110-11” with the XTR M9100 launch, but it was ultimately cancelled and never released.

Shimano Sprocket Mounting Standards

There are many types of freehub bodies, but in fact, there are even more types of sprockets that mount onto them.

Shimano sprockets come in the following types:

※ Additionally, freewheel sprockets also exist.

For 10-speed, 11-speed, and 12-speed sprockets, even if the gear count is the same, the compatible freehub body may differ by model. Be especially careful about compatibility.

Compatibility Between Shimano Freehub Bodies and Sprockets

Here’s a summary of the compatibility between the freehub bodies and sprockets we’ve looked at:

12-Speed Sprocket Compatibility

Key points to remember for Shimano’s 12-speed freehubs and sprockets:

1. MTB-type Micro spline 12-speed sprockets are only compatible with Micro spline freehubs.
2. Road 12-speed sprockets are compatible with HG spline L2 and HG spline L freehubs.

11-Speed Sprocket Compatibility

There are two types of 11-speed sprockets:

• HG spline L 11-speed sprocket
• HG spline M 11-speed sprocket

Which one you use determines the compatible freehub and whether a spacer is needed.

For a more detailed explanation, please refer to the following page:

10-Speed Sprocket Compatibility

There are also two types of 10-speed sprockets:

1. Standard 10-speed sprockets fit HG spline M, same as 8- and 9-speed types.
2. Older road 10-speed sprockets like the CS-7900 are 1mm shorter in height.

The “Old Road 10-speed Sprockets” include:

• CS-7900
• CS-7800
• CS-6700
• CS-6600
• CS-5700
• CS-5600

An easy way to remember them is: 10-speed sprockets from the old DURA-ACE, old ULTEGRA, and old 105.

For a more detailed explanation, please refer to the following page:

How to Identify the Gear Count of a Complete Bike Wheel

To determine “what gear wheel” a complete bike has, the best method is to identify which freehub body is used.

However, it’s rare for bike manufacturers to include the freehub standards in their specifications, so it’s best to check the “sprocket model number” and “whether spacers are used” on the standard equipment installed on the bike.

Frequently Asked Questions About Shimano Sprocket and Wheel Compatibility