There are two requirements for a cassette to be compatible with a particular hub
- The splines of the hub should match the cutout on the cassette. If that condition is not met, there is no way to slide the cassette onto the hub.
- The cassette should be narrow enough to fit on the freehub body.
To ensure that one hub can accept a great number of cassettes of different speeds, the sprockets get thinner and closer to one another as the number of gears increases.
Shimano’s 8, 9, 10, 11 and 12-speed MTB cassettes are close in width.
The table below contains the width of 8-12-speed cassettes:
|NUMBER OF SPEEDS||TOTAL WIDTH|
The width of the cassette is irrelevant when its cutout is incompatible with the splines of the hub. This would be the case for Shimano’s microspline 12-speed cassette.
The 12-speed cassettes from the Microspline family are compatible only with Microspline hubs. Those cassettes cannot be installed on a standard Shimano Hyperglide hub.
That said, 10-speed HyperGlide MTB hubs can accept 12-speed HyperGlide cassettes made by other companies such as SunRace.
Shimano’s 10-speed road cassettes are narrower than 8,9, 11 and 12-speed models. Consequently, the matching hubs are narrower too.
Or in other words, you will be unable to install a 12-speed cassette on a dedicated Shimano 10-speed road cassette due to the lack of space. Those cassettes accept only 10-speed road cassettes and nothing else.
However, an 11-speed hub can also run a 10-speed cassette with the help of spacers to make up for the extra width. Thus, some 10-speed road bikes actually use 11-speed hubs. Those hubs will allow the installation of a 12-speed cassette with matching splines upon removing the spacers.
SRAM’s 12-speed NX and SX cassettes can be installed on standard 10-speed SRAM and Shimano hubs (the type of hubs compatible with the PowerGlide and HyperGlide cassettes).
However, SRAM’s GX cassette requires an XD driver. Therefore, it’s not possible to install a GX cassette on a standard Shimano or SRAM 10-speed hub. This conversion will require a hub with an XD driver.
A 12-speed Campagnolo cassette can be installed on a 10-speed hub, but only when the hub is also made by Campagnolo.
Campagnolo cassettes are not compatible with Shimano and SRAM hubs.
The above can seem a bit complicated and I will therefore summarize it in a simple table:
|Manufacturer||Hub Type||Cassette Compatibility|
|Shimano + SRAM||MTB 10-speed||8, 9, 10, 11 MTB|
12-speed HyperGlide Models
SRAM NX and SX 12-speed models
|Shimano||10-speed Road||only 10-speed road cassettes|
|Campagnolo||10-speed||9,10,11, 12-speed Campagnolo cassettes|
What is the advantage of a 12-speed cassette over a 10-speed model?
- Smoother transitions
The extra cogs on the cassette make the jumps between gears smaller. As a result, the rider can maintain a smooth cadence. Cadence is a term describing the rotations of the cranks per minute. High cadence (e.g., 90 RPM) is associated with higher average speeds and lower energy expenditure.
What are the downsides of installing a 12-speed cassette on a 10-speed hub?
The main downsides of this conversion are the extra expenses. A switch from 10 to 12 speeds will require the following parts:
- New hub (If the current isn’t compatible. The wheel will have to be rebuilt too.)
- New cassette (12-speed cassettes aren’t the cheapest.)
- 12-speed shifter + cable + housing
- New derailleur if the current one cannot cover the entire cassette
- New chain (12-speed chains are narrower to prevent rubbing against the cogs)
- New chainring (the narrow 12-speed chains will bind when used on standard 10-speed chainrings)