The freewheel hub is an essential part of modern racing bikes. A freewheel hub is attached to the main hub of your rear wheel, allowing the wheel to continue turning even when you are not pedaling. It is the extension of the main hub into which the cassette is inserted to ensure the smooth running of the entire circuit. The ratchet mechanism in the freewheel transfers the tremendous pedaling power to the wheel, and the cassette with the group of gears ensures a smooth freewheel that propels your bike forward. A freewheel is the solution to the weaknesses of freewheels. It makes your life easier when it comes to installation, functionality and cleaning.

The most common freewheel hub brands for bicycles

A cassette system is located exactly between the freewheel hub and the chain running above it. In order for the rear wheel to rotate smoothly, the freewheel hub and cassette must be compatible with each other. Although Shimano originally invented the freehub tool, companies like Sram and Campagnolo developed their examples later. Currently, Shimano and SRAM are two big brands that dominate the market. The structure of the teeth and the ratchet mechanism therefore depends on the respective brand. You cannot install SRAM freehubs into Shimano cassettes and vice versa. Let's discuss the issue of compatibility in detail.

Compatibility of Shimano freewheel hubs and cassettes

Shimano is known for its HG or Hyperglide freewheels. It is the most common Freehub design introduced by the brand in the 80s. Although the 9-spline freewheel hub is very popular today, back then the Shimano HG style had 13 spline hubs. The Shimano Hyperglide series provides proper alignment to the cassette so the gear can shift properly.

HG "8-10" Speed ​​Mountain Freehub - Shimano Hyperglide 8-10 Speed ​​Mountain Freehub is compatible with the 8/9/11 Speed ​​Mountain cassette. Shimano's instructions for the 10-speed cassette make the space narrower than previous versions, and a 1mm spacer becomes mandatory to fit the sprocket pack. Finally, the 11-speed road cassette was added, which is not compatible with this version of the freehub.

Shimano HG 10-Speed ​​ONLY Freehub - Shimano HG 10-Speed-Only Freehub is intended exclusively for the 10-speed version, which other cassettes without 10-speed do not fit into. The teeth on this freewheel hub are higher, which is why this version is only suitable for 10-speed Shimano cassettes.

Shimano HG 11/12 Speed ​​Road Freehub - Another standard freehub from Shimano is the HG 11/12 Speed ​​Road Freehub, which is compatible with most Shimano cassettes. It is only suitable for 11 and 12 speed cassettes, but if you have an 8/9/11 speed mountain cassette, they will fit this type of freewheel with a 1.85mm spacer. For a 10-speed cassette, an additional 1 mm spacer is required in addition to the 1.85 mm spacer.

Shimano Micro Spline (MS) 11/12 Speed ​​- As the name suggests, this freehub has 23 micro splines, much more than the usual HG freehubs. Where the regular HG freewheels have 13 spline hubs, this Micro Spline freewheel has twice as many, namely 23 small spline hubs. A narrow freehub means you can only fit a small sprocket, even smaller than 11 teeth. Shimano developed this version for 12-speed MTB cassettes, so it is another exclusive version for 12-speed cassettes.

Shimano Hyperglide+ 12 Speed ​​Road - Recently Shimano introduced another updated version of the 12-speed road variant that looks similar to the Micro Splines freehub. This version of the freewheel hub is only suitable for 12-speed road bike cassettes. No spacer is needed to install the sprocket pack, which is not compatible with 11x. Shimano is reportedly using Hyperglide+ technology in this freehub, previously used in off-road bikes. This example is designed for Dura-Ace (R9200) and Ultegra (R8100) cassettes.

SRAM freehub & cassette compatibility

Another market leader in this category is undoubtedly SRAM. He also offers HG cassettes. Most SRAM freehubs can be divided into two categories: XD and XD-R series. Let's talk about them in detail.

SRAM XD 11 & 12 Speed ​​- The SRAM XD freehub is designed for 11 and 12 speed cassettes. The SRAM XD freehub is completely different from the Shimano HG series and has a unique design. The gearing of the SRAM XD freewheel hub is different than that of the traditional Shimano freewheel hubs. The SRAM XD freehub is lighter than Shimano's Hyperglide series freehubs, and SRAM has made it more durable than others. This XD freewheel is also designed for small 10-tooth sprockets.

XD-R 11 & 12 Speed ​​- Although the SRAM XD series was originally designed for MTB cassettes, the XDR freehub is primarily used for 11 and 12 speed road bikes. It can also accept an XD MTB cassette if you install a 1.85mm spacer.

Compatibility of Campagnolo freewheels and cassettes

Campagnolo also made it onto the list. Campagnolo is known for producing high-quality bicycle components and related accessories. The brand also produces freewheel hubs that are exclusively suitable for Campagnolo cassettes.

Campy 9 & 10 & 11 & 12 Speed ​​- Campy 9/10/11/12 Speed ​​freewheel hubs are only suitable for 9/10/11/12 Speed ​​Ultra-Drive cassettes. You cannot mount other gears on this freewheel hub. You do not need an additional spacer to mount the Campagnolo cassettes mentioned above.

N3W 13 Speed ​​- Campagnolo's N3W freehub was originally developed for the new Campagnolo Ekar gravel groupsets. The distribution of the teeth is similar to Campy, but it is 4.4 mm shorter. It can accommodate 12 or 12 speeds and is completely backwards compatible.

How to determine the speed of the cassette?

The best way to determine your speed is to count the gears on your rear wheel. Your gear may have so many teeth on the sprocket that you can count by counting how big the cassette you are using is. If you have multiple gears, that just proves that you don't have a single-speed bike, but a multi-speed bike. Road bikes usually have smaller sprockets with 11, 12 or 13 teeth than MTB bikes, so the jumps between two gears when shifting are smaller. This also means that your bike can accelerate more efficiently with small sprockets. On the other hand, large sprockets with more teeth and large jumps between gears make life easier when climbing hills.

There are several cases where freewheel hubs can be used with cassettes for which they were not designed. In such cases, a spacer for installing the cassette is very useful. Your freehub may be compatible with multi-speed cassettes with or without spacers. Another point to consider is the derailleur gears. Whatever you install on your bike, your derailleur must also be compatible with smooth shifting, cranking uphill, or increasing the overall riding experience.

Cassette Compatibility Chart