What is a Freehub Body?
The freehub body is the component that sits at the center of the hub.
Its role is to allow the bicycle to coast when you stop pedaling while riding.
Fixed-gear hubs do not have this freehub body; the pedals and the hub are directly connected via the chain, meaning that if you stop moving your legs, the wheels stop, and if you stop pedaling, you cannot move forward.
This photo shows the gear mounting section of a fixed-gear hub.
There are different types of freehub bodies.
There are three major bicycle component manufacturers. Components refer to systems such as shifting or braking.
Just as there are many standards in bicycles, these freehub bodies are specifically designed according to each component manufacturer.
SHIMANO
This is the most common shape, utilizing a basic spline (the grooves carved into the silver section).
There are different types depending on the number of speeds; Shimano offers two main versions: one for 8–10 speeds and one for 11 speeds.
They look almost identical, but be careful because the width of the freehub body differs between 10-speed and lower models and the 11-speed model.
This is the "Micro Spline" model, which supports the latest Shimano 12-speed systems.
It allows for a smaller 10T cog, which matches recent trends in drivetrains where single-chainring setups have become standard.
SRAM
Older SRAM systems used freehub bodies compatible with Shimano, but recent high-end models now use original freehub bodies from the XD series.
While they have a similar shape, there are two versions: XD and XDR, depending on the components used.
The integrated cassette mounted on the XD body contributes to lower weight, quicker installation, and optimized gear ratios.
CAMPAGNOLO
The Italian giant, CAMPAGNOLO.
Their innovative technology and ideas are often ahead of their time. The proprietary or limited standards they constantly introduce may not be kind to your wallet, but they remain an object of desire.
Naturally, as a manufacturer like this, their freehub body is also a proprietary standard.
The photos show freehub bodies for Campagnolo made by CHRIS KING. They have a different design to prioritize efficiency, such as durability and weight reduction.
Always ahead of the times, CAMPAGNOLO's latest components feature the industry-leading 13-speed system.
They are a step ahead of the rest.
The freehub body used for this is also proprietary, and the latest one, called N3W, boasts the incredible performance of covering everything from 13-speed down to 9-speed.
Though, I have only seen it in pictures myself.
These brands are not compatible with each other.
As I have explained, since each manufacturer has its own corresponding cassette for their freehub body, please do not forget to confirm compatibility when preparing parts.
In most cases, there is no cross-manufacturer compatibility, so please be careful.
Are there any other types?
There are others, such as single-speed freewheels or threaded freewheels, where the freewheel mechanism (the part that lets you stop pedaling) is built into the sprocket side.
You don't see things like threaded freewheels very often these days, so I'll save that for another time.
Well then, this time we talked about freehub bodies.
I hope this information is helpful to you.
That's all for today's tip.