Once upon a time, the freehub and cassette pairing was a no-brainer. You only needed to consider whether you were using SRAM, Shimano (the freehub specifications are the same for both), or Campagnolo because those were the only ones on the market. Whether you were using 8-speed, 9-speed, or 10-speed (11-speed Campagnolo only supports its freehub specifications).
But as the number of cassettes continued to increase, things became more and more complicated. When 11-speed was first introduced, it was popular to CNC-cut the cassette or freehub to make it compatible. Fortunately, the freehub and cassette were still kept in their basic form at that time. Today, 11-speed has become the norm, 12-speed has quickly taken over the market, and 13-speed has also been launched. The freehub and cassette pairing problem has become more and more complicated, becoming a bit like the confusion of bottom bracket, bottom bracket, and chainring specifications.
Before we start, let's briefly explain what a freehub is. It is used to install the flywheel and can rotate freely in one direction between the hub shells. It can allow the flywheel to remain stationary when the wheel rotates. We can simply understand it as a "one-way ratchet".
It should be distinguished that the rotary flywheel on the old bicycle is not in our discussion today. Its ratchet structure is installed inside the flywheel. Whether it is compatible or not is only related to whether the hub you choose is a rotary fly hub, and has nothing to do with the freehub and speed.
If you are not sure whether it is a rotary fly or a card fly, you can look at the top cover of your flywheel. If it rotates with the flywheel, it is a card fly. If the flywheel rotates, but the center cover does not move, it is a rotary fly.
About the matching problem between the freehub and the hub
The freehubs between different brands of hubs are not interchangeable with each other. Each brand has its unique ratchet structure. Even if they look similar, there are differences. Even if they are the same brand, due to different models, the freehubs may not be interchangeable. So if you want to replace different types of freehubs, you must choose a freehub that matches the hub for replacement.
Although all freehubs can be replaced, it does not mean that all brands can provide suitable freehubs for your flywheel. For example, Shimano does not provide SRAM's XDR freehub specifications and Campagnolo's freehub specifications. Or some older hubs can no longer buy replaceable freehubs.
It is recommended to choose a wheel set according to your current and future needs to avoid unnecessary trouble and loss when upgrading. For example, SCOM provides a variety of freehub options including Shimano 11-speed, SRAM XDR, Campagnolo 13-speed and below specifications, which can adapt to most flywheel combinations on the market.
What are the common freehub specifications?
HG stands for Hyperglide. It was introduced in 1990 and is still the most popular specification today. It is usually called Shimano specification or 10-speed freehub. There are 9 splines on the freehub, one of which is narrower than the other 8, which is convenient for users to position when installing the flywheel. The diameter of the freehub is about 34mm, which means that the smallest flywheel must be 11T or above.
[The above picture shows an 11-speed mountain bike flywheel, but it can also be installed on a 10-speed freehub, so the freehub is also called a mountain bike freehub]
The overall length of the flywheel installation part of the freehub is 35mm. From the commonly called name 10-speed freehub, you know that it can be used up to 10 speeds (only for road bike flywheels), but for mountain bikes, some 12-speed flywheels can be used.
This freehub can use 7, 8, 9, and 10 road bike flywheels. If you need to use an 11-speed road bike flywheel, you need to remove about 1.85mm from the last center bracket of the flywheel, or the flywheel bracket of some models can be cut inward by 1.85mm. Just remember that 7-10 speed road bikes can be used.
In some cases, Shimano's 10-speed cassettes other than Tiagra require a 1mm washer to be installed at the bottom, which is usually included in the package (the reason will be explained in the HG11-speed freehub). SRAM 10-speed cassettes do not need to be installed.
For mountain bikes, this freehub can be used for 11-speed mountain bike flywheels and some models of 12-speed flywheels, but the minimum flywheel of the 12-speed flywheel must be greater than or equal to 11t. These 12-speed flywheels will suspend the largest flywheel on the outermost side to accommodate a shorter freehub length.
Shimano HG 11
As the name suggests, this freehub is specially designed for 11-speed, and its appearance is almost the same as the 10-speed freehub. The only difference is that the spline length for installing the flywheel has increased by 1.85mm, from 35mm to 36.85mm.
[10-speed freehub on the left, 11-speed freehub on the right]
Shimano and SRAM's 11-speed road flywheels both need to use this longer freehub. Similarly, the new Shimano 12-speed road flywheel is also backward compatible with this 11-speed freehub.
By installing a 1.85mm thick washer at the bottom of the 11-speed freehub, it is compatible with all flywheels installed on the Shimano 10-speed freehub.
[If you want to install a 10-speed flywheel, you need to install a 1.85mm washer on the freehub]
There are several special cases to be explained about HG10 and HG11 speed. Around 2004-2007, Shimano launched a special 10-speed freehub with a shorter length and deeper splines to increase the contact area between the flywheel and the freehub, and further increase the offset on the drive side. But this specification was discontinued soon, so it can only be seen on a few old high-end models. Unless this freehub is completely replaced, it can only use Shimano's 10-speed flywheel. This is why it is said that a 1mm washer needs to be added to the 10-speed freehub.
The second thing to note is that the 11-34T cassette under Shimano's 11-speed road is a re-labeled mountain bike cassette model, so this cassette is designed to be installed on a 10-speed freehub. When you want to install it on an 11-speed freehub, you need to add a 1.85mm washer to the freehub. The 11-36T cassette of SRAM 11-speed does not need to add a washer, it is a pure road bike cassette.
The third interesting thing is about the length of the Shimano freehub on the old Mavic hub. It had reached 36.75mm at the time, which was already capable of installing the current 11-speed Shimano and SRAM, and even Shimano's 12-speed cassette. So, when you need to install an 8-10 speed cassette on these freehubs, you need to install a 1.75mm (1.85 is also acceptable) washer.
The fourth is about 6-speed and 7-speed card fly. The overall height of these flywheels is lower, so when installing, you need to add a thicker washer. Whether it is HG10 or HG11, add a 4.5mm washer to use it. But on the other hand, the new 8-12 speed flywheel cannot be installed on the old 7-speed freewheel body. (Just know, it is rarely seen.)
Shimano Microspline\Mountain Bike 12-speed freewheel body
To compete with SRAM's XD freewheel body, Shimano also launched the Microspline freewheel body. You can use the smallest 10T flywheel, the splines on the freewheel body are more, denser, and shorter (26mm). The design is roughly the same as the design idea of XD, allowing the smallest 10T flywheel to hang on the outside of the freewheel body.
Although it is called a 12-speed freewheel body, it can also install an 11-speed flywheel, but only the 11-speed and 12-speed flywheels with the smallest 10T of Shimano specifications can be used. In addition, there are almost no other specifications of flywheels that can be installed on this freewheel body.
Unlike XD freehubs, which can be produced without authorization, Shimano's Microspline freehubs require authorization to be produced. Currently, in addition to Shimano, DT SWISS, Hped, Bontrager, Stan's NoTube, Industry Nine, and other hubs all provide the option of this freehub. Similarly, companies such as Garbaruk also provide flywheels that support this freehub.
Shimano EV road freehub
With the launch of the Shimano 12-speed road bike kit, Shimano also released a freehub specifically for the new kit. However, using the new 12-speed flywheel does not require a dedicated freehub, which is often called backward compatibility.
Shimano 12-speed road bike flywheels are compatible with the common 11-speed Shimano freehub. The new 12-speed EV freehub only adds more splines to disperse the load applied by the flywheel on the aluminum alloy freehub and reduce the damage of the flywheel to the freehub.
Shimano EV freehub can only be used with the new road 12-speed flywheel. Including 12-speed mountain bike cassettes, none of them can be installed on the EV freehub. Currently, only Shimano provides EV-spec hubs.
SRAM XD freehub
SRAM XD freehub is specially designed for its mountain bike kit, to make the flywheel have a wider gear ratio. HG freehub is only compatible with the smallest 11t flywheel, so XD freehub came into being. XD freehub uses an integrated flywheel, which is fixed to the freehub with threads on the back of the flywheel.
SRAM XD freehub is only suitable for SRAM 11 and 12-speed mountain bike flywheels less than 11T (excluding 11T), including 10-42T flywheels for gravel. All SRAM flywheels equipped with the smallest 11T flywheel use HG freehub.
To allow XD freehub to occupy the market faster, SRAM can provide it to other brands without authorization. Almost all hub brands on the market currently offer XD freehub options. The only exception is Shimano, which has only been on its platform so far.
Shimano XD-spec cassettes are installed and removed using the same tools as HG10, HG11, Shimano EV, and Microspline, including a cassette cover wrench and chain wrench.
Sram XDR freehub
Sram XDR is the road version of XD, which is only 1.85mm taller than the XD freehub (just like HG11 is 1.85mm taller than HG11). The XDR freehub is suitable for SRAM's 12-speed road cassettes and XPLR cassettes.
Similarly, you can also install a 1.85mm spacer on the XDR freehub to use a cassette installed on the XD freehub. And the spacer specifications are the same as those installed on the HG11.
Campagnolo freehub\CP freehub
For a long time, CP (campagnolo) has always had its own set of freehub specifications, from 9 speed to today's 12 speed, and even 13 speed (downward compatibility requires adapters). CP freehub is compatible with all CP's cassettes from 9 to 12 speeds. The only thing you need to make sure is whether your cassette is a Campagnolo cassette.
It should be noted that CP's cassette locking cover tool is different from the sima and SRAM cassette removal and installation tools mentioned above.
Although the swivel tool and CP's cassette cover removal tool are not the same, the difference is very subtle and can be used interchangeably. So, if you want to remove a CP cassette, you don't need to purchase a CP special tool. You only need a swivel cassette removal wrench and a chain whip.
It should be noted that the 8-speed CP cassette requires a special CP 8-speed freehub to match, so it is not suitable for existing specifications.
Campagnolo N3W freehub\13-speed freehub
Like the HG specification, the CP freehub can only install a minimum 11T cassette. So, when Campagnolo launched the Ekar 1X 13-speed kit, they also brought a shorter freehub that can be installed with the smallest 9T sprocket: N3W.
The N3W has the same spline shape as the old CP freehub, but is 4.4mm shorter overall. Currently, only Ekar's 13-speed cassette can be installed on this freehub, and vice versa, Ekar's 13-speed cassette can only be used on the N3W freehub.
A conversion block was also released that can be installed on the N3W to adapt to CP's 9-12-speed cassette. When the N3W needs to be installed with a 9-12-speed cassette, first, a dedicated conversion block is required, and second, a dedicated sprocket cover is required. The conversion block can complete the N3W freehub to the appropriate length, and the longer sprocket cover can lock the sprocket on the body of the N3W freehub.
Currently, the hub and wheel brands that support N3W freehub include Campagnolo, Fulcrum, Mavic, DT SWISS, FFWD, Hunt and other brands that are catering to the new specifications. In addition, many brands of wheels use the same internal structure as DT, so these hubs can also be replaced with the N3W freehub provided by DT.
Summary
First, determine the speed of the flywheel, and then determine the number of teeth of the smallest flywheel. If it is below 11T, it is the latest specification freehub (Microspline, XD\XDR, N3W). The smallest flywheel of 11T and above is the Shimano HG specification. Basically, remember these two points, and then combine them with the flywheel brand, you can identify 90% compatibility.
Other flywheels with special installation methods such as e-13 will not be further subdivided. I believe that players who choose this type of flywheel should be familiar with compatibility.
If you have anything to add, please leave a message below.
Tags #carbon wheels #Superteamwheels #Sram #Shimano #Campagnolo
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