When choosing an MTB hub or upgrading a wheelset, one of the most frequently asked questions is:
“Will my cassette fit this hub?”
The answer depends entirely on the freehub standard — the interface between your wheel’s hub and your cassette.
Choosing the wrong freehub means the cassette will not mount properly, even if the hub matches your frame spacing.
This guide explains the key differences between Shimano HG, Shimano MicroSpline, SRAM XD/XDR, and Campagnolo, and how each standard affects compatibility with modern MTB drivetrains.
🔸 Why Freehub Standards Matter
Each drivetrain brand uses its own spline pattern, length, and design philosophy.
A quick summary:
- Shimano HG → 8–11 speed MTB/Road
- Shimano MicroSpline → 12-speed MTB
- SRAM XD → 11/12-speed MTB
- SRAM XDR → 12-speed Road/Gravel
- Campagnolo → Dedicated CP freehub
- Single Speed → Narrow body for 1-speed setups
1. Shimano HG (Hyperglide) Freehub
The most widely used freehub standard in the cycling industry.
✔ Compatible With:
- Shimano 8/9/10/11-speed MTB cassettes
- Most SRAM 10–11 speed cassettes
- Many third-party cassettes (SunRace, MicroSHIFT)
HG Variants
MTB 10S HG — 35 mm
Used for:
- himano 8/9/10-speed mountain cassettes
Road 11S HG — 36.8 mm
Used for:
- Shimano 11-speed road cassettes
When installing a 10-speed road cassette, a 1.85 mm spacer is required.
Even though different brands adjust the length slightly, the spline shape remains identical, ensuring universal fit.
ALT: Shimano HG freehub body for MTB hubs — standard spline design
2. Shimano MicroSpline Freehub
Created for Shimano’s 12-speed MTB drivetrains, including:
- Deore
- SLX
- XT
- XTR
Key Features
- 23 micro-splines (more contact area, less wear)
- Allows 10T smallest cog
- Not backward compatible with HG
- Only works with 12-speed Shimano MTB cassettes
Koova is currently developing our MicroSpline version for future hub releases.
3. SRAM XD Freehub (MTB)
The XD driver is the standard for SRAM 11/12-speed MTB drivetrains:
- GX
- X01
- XX1
- SRAM Eagle systems
Key Features
- Threaded interface
- Shorter body (~34 mm)
- Allows 10T smallest cog
- Not compatible with Shimano HG or MicroSpline
If your cassette label says “XD Driver” or starts with 10T, you need an XD freehub.
4. SRAM XDR Freehub (Road / Gravel)
XDR is the road version of XD, extended slightly to support road spacing.
Key Features
- Longer than XD (~37 mm)
- XDR cassettes fit directly
- XD cassettes can be used with a 1.85 mm spacer
If you're using SRAM eTap AXS on road or gravel, you need XDR, not XD.
5. Campagnolo Freehub (CP)
Campagnolo uses a unique 3-spline pattern distinct from all Shimano/SRAM designs.
Compatible With:
- Chorus
- Record
- Super Record
Koova will introduce a CP option in upcoming models.
6. Single Speed Freehub
Designed specifically for 1-speed drivetrains, featuring:
- Narrower body (~28 mm)
- Fits a single cog with lockring
- Ideal for urban, track, and messenger setups
🔧 Final Recommendations
Freehub standards are essential for ensuring correct cassette fitment and avoiding drivetrain issues.
Koova hubs are built using:
- Precision-machined hub shells
- High-durability bearings
- Modular freehub systems for cross-brand compatibility
If you're unsure which freehub your cassette needs:
👉 Send us a photo (or your drivetrain model).
Our Koova support team will identify the correct freehub instantly.