Which Freewheel Fits My Wheel? Simple Guide for Road, MTB & Gravel Bikes

If you want to upgrade your wheel, change the cassette, or switch to a new groupset system, the question quickly arises: Which freehub actually fits my wheel?

Especially for road bikes, gravel bikes, and MTBs, there are now several different freehub standards – and unfortunately, they are not all compatible with each other.

In this guide, we will take a practical look at:

• which freehub types exist,
• how to identify what is installed on your wheel,
• what fits Shimano, SRAM, Campagnolo & Co.,
• and what to look out for when buying new wheels or hubs.

What is a freehub – and why is it important?

The freehub body sits on the rear hub and is the part onto which you slide your cassette. It fulfills two tasks:

1. Power transmission: When you pedal, pawls or a tooth system engage and drive the wheel.
2. Freewheeling: When you stop pedaling, the wheel can continue to rotate while the crank remains stationary – hence the familiar clicking sound.

For your cassette to fit, these three things must match:

• Freehub standard (e.g., Shimano HG, Micro Spline, SRAM XD, XDR, or Campagnolo)
• Number of cogs (8-/9-/10-/11-/12-speed)
• Application area (road bike, MTB, gravel, or e-bike)

That's why the question "Which freehub fits my wheel?" is so important before you order something.

Overview of the most important freehub standards

Shimano HG – the classic

Application:

• older and many current road bikes up to 11-speed
• many MTBs with 8- to 11-speed
• many trekking and city bikes

Features:

• slightly conical shape with splines
• 8- to 11-speed cassettes fit depending on the version
• many Shimano and SRAM cassettes are suitable for it

Typically suitable for:

• Shimano 8-/9-/10-/11-speed cassettes
• many SRAM 8-/9-/10-speed cassettes

If you are looking for a new cassette for your HG freehub, you will find suitable models in our Cassettes & Cogs category.

Shimano Micro Spline – modern MTB standard

Application:

• modern MTBs with Shimano 12-speed
• for example, Deore, SLX, XT, or XTR 12-speed

Features:

• many small, fine splines
• developed for 10-tooth minimum cog
• not compatible with classic HG cassettes

Typically suitable for:

• Shimano 12-speed MTB cassettes with 10-tooth cog, for example 10–51

So if you ride a modern 12-speed Shimano MTB, it's highly likely that you have a Micro Spline freehub.

SRAM XD and XDR – for modern SRAM drivetrains

SRAM XD (MTB)

• for 12-speed MTB cassettes with 10-tooth cog, for example SRAM Eagle
• narrow, special freehub body

SRAM XDR (Road / Gravel)

• for modern 12-speed road and gravel cassettes from SRAM
• similar to XD, but slightly longer

Important:

• XD and XDR are not compatible with Shimano HG or Micro Spline
• many modern gravel and road bike wheels are available in variants with XDR

Campagnolo freehub

Application:

• road bikes with Campagnolo groupsets

Features:

• own spline geometry
• Campagnolo cassettes require Campagnolo-specific freehubs

If you ride a classic Campagnolo road bike, a suitable Campagnolo freehub is usually installed.

How do I find out which freehub I have?

Before you buy anything, you should check which system is installed on your wheel.

Step 1 – Check what is currently mounted on your wheel

1. Turn the bike upside down or place it in a repair stand
2. Remove the rear wheel
3. Examine the cassette and hub more closely

Ask yourself these questions:

• Which groupset do you ride – Shimano, SRAM, or Campagnolo?
• How many cogs does your cassette have?
• Do you ride a road bike, gravel bike, MTB, city bike, or e-bike?

These details often provide initial clues about the installed freehub standard.

Step 2 – Remove the cassette and examine the freehub body

To be absolutely sure, it is best to briefly remove the cassette. For this, you usually need:

• cassette tool
• chain whip
• a wrench, if necessary

Once the cassette is off, you can see the bare freehub body:

• coarse splines = usually Shimano HG
• many small, fine splines = usually Micro Spline
• narrow special shape = possibly XD or XDR
• significantly different spline geometry = probably Campagnolo

When in doubt, simply take a photo of the freehub and cassette and compare it with product images or ask us.

Step 3 – Check imprints and manufacturer specifications

Many hubs or wheels have indications such as:

• Shimano HG
• Micro Spline
• XD or XDR
• Campagnolo

It's also worth checking:

• the wheel manufacturer's website
• the owner's manual
• the product description in the shop

If you bought your wheel or hub from us, you will find many details directly in the product description. An overview can be found here:

• Wheels
• Hubs & Accessories

Which freehub fits which cassette?

Shimano HG

Compatible with:

• Shimano 8-/9-/10-/11-speed road and MTB cassettes
• many SRAM 8-/9-/10-speed cassettes
• partially 11-speed road cassettes from other manufacturers

Not compatible with:

• Shimano 12-speed MTB with Micro Spline
• SRAM XD / XDR
• Campagnolo

Micro Spline

Compatible with:

• Shimano 12-speed MTB cassettes with 10-tooth cog

Not compatible with:

• older Shimano HG cassettes
• SRAM XD / XDR
• Campagnolo

SRAM XD / XDR

XD (MTB):

• for SRAM 11-/12-speed MTB cassettes with small 10-tooth cog

XDR (Road/Gravel):

• for SRAM 12-speed road and gravel cassettes

Both not compatible with:

• Shimano HG and Micro Spline
• Campagnolo

Campagnolo

Compatible with:

• Campagnolo-specific cassettes

Not compatible with:

• Shimano / SRAM HG
• Micro Spline
• XD / XDR

What to do if the freehub doesn't fit?

1. Only replace the freehub body

Many wheels offer interchangeable freehub bodies. This is often the most cost-effective solution.

Here's how to proceed:

1. Check which hub you have
2. See if the manufacturer offers replacement freehub bodies
3. Choose the appropriate standard, for example HG, XDR, or Micro Spline
4. Have it professionally installed or install it yourself

You can find suitable hubs and accessories here: Hubs & Accessories.

2. Replace complete wheels

If your wheels are already older or you are planning an upgrade anyway, it may be sensible to directly buy a new rear wheel or a new wheelset with a suitable freehub.

This is often worthwhile for:

• switching to 12-speed MTB
• switching to AXS in the road or gravel sector
• upgrading entry-level wheels

You can find suitable models here:

• Wheels & Wheelsets
• Rear Wheels

3. Stick with the existing system

If your drivetrain works well and you are not planning a complete upgrade, it is often easiest to simply stick with your current freehub standard and choose a new cassette in the same system.

Go directly to our cassettes here.

Typical practical examples

Older road bike with 10-speed Shimano

If you ride a 10-speed Shimano 105, your rear wheel most likely has a Shimano HG freehub installed. You can then easily mount a suitable 10-speed cassette again.

New MTB with Shimano Deore 12-speed

On a modern MTB with Deore 12-speed, a Micro Spline freehub is usually installed. You will then also need a suitable Shimano 12-speed MTB cassette with a 10-tooth cog.

Gravel bike with SRAM Rival eTap AXS

If you ride a modern gravel bike with SRAM Rival AXS 12-speed, an XDR freehub is usually installed. If you buy new wheels, you should therefore specifically look for XDR.

Conclusion – How to quickly find the right freehub

If you want to find out which freehub fits your wheel, it's best to proceed as follows:

1. Check current cassette and groupset
2. Identify wheel or hub model
3. Examine the freehub body
4. Check manufacturer specifications and product description

If you are unsure, simply take some good photos of the cassette, freehub, and hub and ask us.

Find suitable components directly

If you now know which freehub is on your wheel, you can specifically look for compatible parts:

• Wheels & Wheelsets
• Rear Wheels
• Hubs & Accessories
• Cassettes & Drivetrain