Road bike freehub body: HG, XDR, N3W — how to identify yours

The freehub body is undoubtedly the most decisive — and often the least understood — component when it comes to installing a new cassette. Even before considering the number of speeds or the brand, it determines whether your cassette can physically fit onto your wheel. Many disappointments when buying a used cassette come from a freehub body that was not checked beforehand.

This guide explains what a freehub body is, the different standards available (HG, XD/XDR, N3W), and how to identify yours before choosing your next road bike cassette. For all compatibility points, you can also check your cassette compatibility with our dedicated guide.

1. What is a freehub body and why is it so important

The freehub body is the cylindrical, splined component attached to the rear hub, onto which the cassette slides and locks into place. It transfers pedalling power from the cassette to the wheel through a pawl mechanism. Its shape — the number and profile of its splines — must exactly match the cassette design: two different standards simply cannot fit together, regardless of the cassette or derailleur brand.

Three major freehub body families currently dominate the road cycling market: HG, XD/XDR, and N3W.

2. Shimano freehub body (HG / Hyperglide)

HG Standard (Hyperglide)

🇯🇵 Shimano · Most widespread standard · Multi-brand compatible

Compatible brands Shimano, SRAM (≤11-speed), multi-brand cassettes

Speeds 8 to 11-speed (some 12-speed models)

Common on used wheels Very high

Common on used wheels

4.8/5

Ease of identification

4.5/5

Cross-brand compatibility

4.4/5

The Hyperglide (HG) freehub body is the historic standard developed by Shimano and is now widely shared by SRAM for its cassettes up to 11 speeds. It is the most common freehub body found on used wheels currently available, especially for Shimano 10-speed and 11-speed cassettes, as well as equivalent-generation mechanical SRAM cassettes. If your wheel originally came on a bike equipped with Shimano or non-AXS SRAM components, there is a strong chance it uses an HG freehub body.

3. SRAM freehub body (XD / XDR)

XD and XDR Standards

🇺🇸 SRAM · 12-speed standard · XD (MTB) / XDR (Road)

XD MTB origin, shorter version

XDR Road version, +1.85 mm compared to XD

Compatibility with HG None, dedicated component required

Common on recent wheels

3.9/5

Common on used wheels

2.3/5

Ease of identification

4.1/5

The SRAM XD freehub body was introduced to allow a 10-tooth smallest sprocket to be mounted directly onto the freehub body rather than onto the cassette itself. Its road version, XDR, is slightly longer (approximately 1.85 mm longer) to comply with standard road wheel spacing. An XD freehub body cannot accept a road cassette designed for an XDR body, and vice versa: they are two distinct components despite their similar names.

This standard mainly applies to SRAM 12-speed AXS cassettes (Rival, Force, Red) — for detailed information about the different ranges, see our article on SRAM 12-speed cassettes. It is still uncommon on older used wheels, but is becoming increasingly widespread on wheels sold in recent years.

4. Campagnolo freehub body (N3W) and Micro Spline

N3W and Micro Spline Standards

🇮🇹 Campagnolo / 🇯🇵 Shimano MTB · Specific standards · Special cases

N3W Campagnolo Super Record S, Chorus 13-speed

Micro Spline Shimano MTB/gravel 12-speed (XTR, XT, GRX)

Common on road bikes Very rare

The N3W ("New 3-pawl") standard is used on the latest Campagnolo wireless groupsets with 13 speeds. It remains, to date, exclusive to Campagnolo and is not interchangeable with HG or XDR freehub bodies — for Campagnolo cassettes with 11 speeds or fewer, the classic HG standard still applies. See our article on Campagnolo cassettes for details about the compatible ranges.

The Micro Spline standard, developed by Shimano, mainly concerns MTB and gravel applications (12-speed cassettes with a 10-tooth smallest sprocket). It is rarely found on pure road bike wheels, but may appear on some versatile road/gravel wheelsets — a point worth checking if your wheel was originally supplied with this type of bike.

5. How to identify your wheel's freehub body

According to your wheel brand

Wheel brands such as DT Swiss or American Classic generally offer several interchangeable freehub bodies for the same hub model — the exact reference of your wheel (often engraved on the hub) allows you to determine which one is installed and whether it can be changed without replacing the entire wheel.

Through measurement and direct observation

If no reference is available, direct inspection remains reliable: an HG freehub body has fine, evenly spaced splines around its entire circumference. An XD/XDR freehub body can be identified by a wider asymmetrical spline near the base, designed to accommodate the 10-tooth smallest sprocket. If you already have a cassette in hand, it simply will not slide onto an incompatible freehub body — never force the installation.

Tip: Before ordering a used cassette, first identify the exact reference of your rear wheel. This quick check, which only takes a few minutes, prevents the vast majority of compatibility-related returns.

6. Freehub body and cassette compatibility: key points to remember

The freehub body is only one of the three compatibility points to check before buying a cassette — the other two being the derailleur (cage capacity, number of speeds) and the chain (suitable width). For the complete verification method, see our full guide on cassette, derailleur and chain compatibility.

Key points: HG remains the most common standard on used wheels (Shimano and SRAM ≤11-speed). XD/XDR is used for SRAM 12-speed AXS cassettes. N3W is exclusive to Campagnolo 13-speed systems. Micro Spline is mainly used for MTB/gravel applications. Always check the exact reference of your wheel before making any purchase.

View compatible road bike cassettes →

7. FAQ — Road bike freehub body

How do I know which freehub body my wheel has?

The most reliable method is to find the exact reference of your wheel or hub (often engraved on the component) and consult the manufacturer's technical specifications. If this information is unavailable, direct inspection of the splines can help identify the most common standards: fine and evenly spaced splines for an HG freehub body, a wider asymmetrical spline for an XD/XDR freehub body.

Can you change the freehub body without replacing the wheel?

On many wheels with modular hubs (especially DT Swiss or American Classic), yes: the freehub body is an interchangeable component that can be replaced independently from the rest of the wheel. On other wheels, the freehub body is integrated into the hub and cannot be replaced separately — check your model's technical specifications before considering this option.

Is the HG freehub body compatible between Shimano and SRAM?

Yes, in most cases for cassettes up to 11 speeds: Shimano and SRAM share the same HG standard within this range, allowing a certain level of cross-brand compatibility. This does not apply to SRAM 12-speed AXS cassettes, which require a dedicated XDR freehub body.

Is an XDR freehub body required for all 12-speed cassettes?

No. The XDR standard specifically applies to SRAM 12-speed AXS road cassettes. Shimano 12-speed cassettes can use either an HG or Micro Spline freehub body depending on the range, while Campagnolo 13-speed cassettes use the N3W standard. Always check the specific compatibility requirements for your cassette brand and product range.

Road bike freewheel