Condensed answer: The spacings of Shimano and Campagnolo cassettes are different and so are the rear shift ratios of both brands’ derailleurs.
Consequently, a Campagnolo derailleur will not move the chain to the right locations for a shift to occur when using a Shimano cassette in an indexed system. (If the shifter operates in friction mode, the combination will work.)
However, there’s one exception – Shimano’s 11-speed road cassettes. Those can be integrated into a Campagnolo groupset.
Index Shifting
To understand why drivetrain components of different speeds and brands might not mix well, one has to become acquainted with the term index shifting.
Modern drivetrains are indexed so that the rider doesn’t have to think much when initiating a shift. The shifter’s amplitude is segmented into distinct clicks corresponding to the number of gears. Each click pulls or releases a pre-determined (unchangeable) amount of gear cable for a shift to occur.
The rear and front derailleur have a shifting ratio. The shifting ratio describes how much a derailleur moves per 1mm of cable pulled or released by the shifter.
If the ratio is 1:1.7 for example, then the derailleur moves 1.7mm per 1mm of cable pulled or released by the shifter.
The pre-determined cable pull/release and the derailleur ratio result in precise and predictable movement of the derailleur.
The final piece needed for smooth shifting is a cassette with a cog pitch made for the derailleur’s travel. The cog pitch is the center-to-center distance between two cogs.
If one of the three variables (cable pull/release, derailleur ratio, cog pitch) is off, then the shifting experience will not be optimal.
Friction Shifters
Friction shifting is what people had before the modern indexed systems.
A friction shifter moves as much as the rider decides. Or in other words, it’s not restricted and segmented into individual clicks. It’s up to the user to determine the correct position of the shifter for a shift to occur.
The downside of this approach is that the user has to guess, especially in the beginning. Index shifting, on the other hand, is automatic and thus faster.
However, friction shifters are still used for two reasons:
- Affordable
- Compatibility
A friction shifter is compatible with MTB and road parts of all kinds precisely because it’s “free”. Hence why people who like to make unconventional drivetrain mixtures rely on friction shifters.
Shimano Cassette + Campagnolo Derailleur?
If a Shimano cassette and a Campagnolo derailleur are combined in an indexed drivetrain, the combination will often be problematic due to the dissimilar rear shift ratio of the derailleurs.
The table below contains the cable pull ratio of Shimano and Campagnolo derailleurs:
| Brand | Number of Speeds | Rear Shift Ratio (MTB) | Rear Shift Ratio (Road) |
| Shimano | 8 | 1.7 | 1.7 |
| Shimano | 9 | 1.7 | 1.7 |
| Shimano | 10 | 1.2 | 1.7 |
| Shimano | 11 | 1.2 | 1.4 |
| Shimano | 12 | 1.2 | 1.4 |
| Campagnolo | 8 | – | 1.4 |
| Campagnolo | 9 | – | 1.5 (old 1.4) |
| Campagnolo | 10 | – | 1.5 |
| Campagnolo | 11 | – | 1.5 |
| SRAM | 8 | 1.1 | 1.1 |
| SRAM | 9 | 1.1 | 1.1 |
| SRAM Exact Actuation | 10 | 1.3 | 1.3 |
| SRAM Exact Actuation | 11 | – | 1.3 |
| SRAM X-Actuation | 11 | 1.12 | 1.12 |
| SRAM X-Actuation | 12 | 1.01 | 1.01 |
The next table contains the cable pull of many MTB and road shifters:
| Brand | Speeds | Cable Pull (road) | Cable Pull (MTB) |
| Shimano | 8 | 2.8 | 2.8 |
| Shimano | 9 | 2.5 | 2.5 |
| Shimano | 10 | 2.3 | 3.4 |
| Campagnolo | 8 | 3.5 | – |
| Campagnolo | 9 | 3.0 | – |
| Campagnolo | 10 | 2.8 | – |
| Campagnolo | 11 | 2.6 | – |
| SRAM | 8 | 4.3 | 4.3 |
| SRAM | 9 | 4 | 4 |
| SRAM Exact Actuation | 10 | 3.1 | 3.1 |
| SRAM Exact Actuation | 11 | 3.1 | – |
| SRAM (X-Actuation) | 11 | – | 3.48 |
For the most part, the shift ratios do not match. However, there’s an exception. 11-speed Shimano road derailleurs have an approximately 1.4 rear shift ratio and so do Campagnolo’s 8-speed derailleurs as well as the old 9-speed models.
Therefore, at least theoretically, an 8-speed (or an old 9-speed) Campagnolo derailleur would move accurately enough when combined with an 11-speed Shimano cassette and shifter. The Shimano shifter is needed because Campagnolo shifters have a different cable pull.
That said, in practice, the combination isn’t all that viable because those derailleurs are hard to find and many of them have a very short cage that cannot cover a cassette with a large cog over 32 teeth.
The next possible combination is an 11-speed Shimano road cassette with a 9/10/11-speed Campagnolo derailleur. 9/10/11-speed Campagnolo derailleurs have a 1.5 rear shift ratio which is very similar to that of 11-speed Shimano road derailleurs (1.4). Consequently, there’s a lot of anecdotal evidence showing that this combination works.
That being said, flawless shifting is not expected right away. It will be necessary to play with the derailleur’s B-tension screw as well as the gear cable tension.
Summary: What You Need To Know
- In an indexed shifting system, it’s difficult to integrate a Shimano cassette in a Campagnolo drivetrain due to the non-matching spacings of the cassettes as well as the dissimilar rear shift ratios.
- If a friction shifter is used, then it’s possible to combine all sorts of cassettes and derailleurs because there are no restrictions.
- There’s a lot of anecdotal evidence showing that it’s possible to combine an 11-speed Shimano cassette with a Campagnolo drivetrain.
