Condensed Answer: Campagnolo cassettes have a specific cutout preventing them from sliding onto standard Shimano hubs.
If you want to use a Campagnolo cassette, there are two options – replace the freehub body or the entire hub with a compatible one.
The Difference Between Campagnolo and Shimano Hubs
Cassette and hub compatibility is before all dependent on the splines found on the freehub body. The freehub body is the part of the hub on which the cassette slides.
The image below shows a 9/10/11-speed Campagnolo freehub body.
The new image shows a hub designed for 8/10/11 speed Shimano cassettes:
The Campagnolo hub has 8 splines with a “V” shape. Meanwhile, the Shimano hub has 13 splines with a standard square shape.
Those architectural differences make it impossible to directly slide a Campagnolo cassette on a Shimano hub.
Campagnolo has a hub optimized for 12 and 13-speed cassettes. The hub is called N3W. Meanwhile, Shimano uses a microspline hub for 12-speed cassettes. As the name suggests, the microspline hub has many “mini” splines.
If you want to use a Campagnolo cassette with a Shimano hub/wheel, the options are:
- Replace the freehub body of the Shimano hub with one that accepts Campagnolo cassettes
In some cases, it’s possible to remove the Shimano freehub and install a Campagnolo one. One example would be the freehub Campagnolo FH-BUU015 which is suitable for 9/10/11 speed Campagnolo cassettes.
- Replace the entire hub
If a suitable freehub body is not available (e.g., you have a microspline hub), the next option is to simply replace the entire hub with a Campagnolo one.
The advantage of this approach is that it always works. The downside is that the entire rear wheel will have to be rebuilt. The procedure has the following steps:
- Purchase a new hub for the Campagnolo cassette and calculate how long the new spokes have to be. (The new hub will have a flange of a different length and will therefore require a new set of spokes.)
- Unlace the old spokes.
- Re-lace the wheel with the new spokes.
- Tighten the new spokes and true the wheel.
As you can see, this is a lengthy procedure and requires a certain degree of wheel-building expertise as well as tools that some mechanics don’t have (e.g., a truing stand).
The Most Economic Solution
Without a doubt, the most economical solution is to simply give up on the conversion and purchase a Shimano cassette for your hub. The Shimano cassette will more than likely cost less than a new freehub body or the entire hub replacement.
Summary: What You Need To Know
- Campagnolo and Shimano have freehub bodies with completely different spline patterns.
- It’s not possible to install a Campagnolo cassette on a Shimano hub and vice versa right away.
- If the freehub body is replaced with one designed for a Campagnolo cassette, the conversion will work.
- Replacing the entire hub just to fit a Campagnolo cassette requires too much work. It often makes more sense to simply get a Shimano cassette for that particular setup.