Condensed Answer: The cable pull of indexed Campagnolo shifters is different from that of Shimano shifters. Consequently, using Campagnolo shifters with a Shimano derailleur will result in a less than ideal shifting most of the time.
That said, some combinations could offer a passable performance. For best results and minimum frustration, however, it’s recommended to stick to the original shifters.
Cable Pull and Rear Shift Ratio Explained
Modern bicycles shifters are “indexed”. The travel of the shifter is segmented into clearly divided parts. Each upshift or downshift represents one section. The shifters make a click to inform the rider that a new section has been reached.
The rider can move from one section to another but cannot stay in-between because the derailleur won’t be in an optimal position. As a result, the chain will fail to grab the teeth of a rear cog.
The advantage of indexed shifters is that the rider doesn’t have to guess how much to move the shifter to trigger a shift. One click equals one shift.
The “pre-determination” of indexed shifters is achieved via the principles outlined below:
1. Each click pulls or releases a pre-determined amount of gear cable. That amount is known as cable pull.
2. The derailleur has a shift ratio. The shift ratio describes how much the derailleur moves per 1mm of gear cable pulled or released by the shifter.
3. The cable pull of the shifter and the shift ratio of the derailleur are dependent on the number of gears and the spacing of the rear cogs.
For that reason, an 8-speed derailleur and an 8-speed shifter have a different rear shift ratio and cable pull than an 11-speed derailleur and a 10-speed shifter.
If the 8-speed shifter is replaced with an 11-speed one, the derailleur will not move to the accurate location for a shift to occur.
The cable pull of 8-speed Campagnolo shifters is 3.5mm. The rear shift ratio of an 8-speed Campagnolo derailleur is 1.4. Thus, each click/shift moves the derailleur 3.5mm x 1.4 = 4.9mm.
Meanwhile, the cable pull of 11-speed Campagnolo shifters is 2.6mm. If that shifter is used with an 8-speed derailleur, the derailleur will move 2.6mm x 1.4 = 3.64mm per shift. As a result, the chain will fail to reach the desired cog.
Conclusion: If the cable pull of two indexed shifters differs greatly, they are not interchangeable.
Compatibility of Campagnolo Shifters and Shimano Derailleurs
For a Campagnolo shifter to be compatible with a Shimano derailleur by default, it needs to have a cable pull matching that of the original Shimano shifter designed for the mech in question.
Below is a table containing the cable pulls of Campagnolo and Shimano shifters. None of Campagnolo’s shifters match the requirement outlined above:
|Number of Speeds||Campagnolo||Shimano|
|9||3.2mm (old), 3.0mm (new)||2.5mm|
|10||2.8mm||2.3mm (road), 3.4mm (MTB)|
|11||2.6mm||2.7mm (road), 3.6mm (MTB)|
In the next table, you see the rear shift ratio of the respective Campagnolo and Shimano derailleurs:
Rear Shift Ratios
|Number of Speeds||Campagnolo||Shimano|
|9||1.4 (old), 1.5 (new)||1.7|
|10||1.5||1.7 (road), 1.2 (MTB)|
|11||1.5||1.4 (road), 1.1 (MTB)|
At first, glance the tables above present complete non-compatibility. And that would be correct if you want to use a Campagnolo shifter to replace a Shimano shifter designed for the same number of gears.
However, if we combine a shifter and a derailleur designed for a different number of speeds, viable combinations appear.
In order for that to happen, it’s necessary to satisfy the following criteria:
1. The new shifter and the one being replaced should have the same or extremely close cable pulls.
2. The derailleur that we use should have a rear shift ratio that’s the same or extremely close to that used by the original derailleur designed for the cassette in question.
10-speed Campagnolo Shifter + 8-speed Shimano Derailleur + 8-speed Shimano Cassette
A 10-speed Campagnolo shifter has a 2.8mm cable pull. An 8-speed Shimano shifter has the same pull. Thus, if we look strictly at the cable pull data, the two are interchangeable.
If a 10-speed Campagnolo shifter is combined with an 8-speed Shimano derailleur, the derailleur will be controlled as if the shifter is originally designed for the mech in question.
However, the combination will work only if the cassette is also an 8-speed model designed by Shimano.
If we use a 10-speed cassette, the derailleur will move tоo much for smooth shifting.
(10-speed cassettes have smaller spacing between the gears and require shorter derailleur movements).
Problem: Obviously, 10-speed shifters have 2 more clicks than 8-speed shifters. This leads us to a logical question – what happens to the extra shifts when using an 8-speed cassette?
If the limit screw of the rear derailleur is not adjusted properly, a 10-speed shifter could throw the chain into the spokes or the frame and create an accident.
However, if the limit screws are properly adjusted, the derailleur will be physically prevented from over-shifting and pushing the chain outside of the cassette.
The shifter will still have 2 “phantom” gears. Or in other words, when the user shifts to speed 9 and 10, the chain will not move. This creates an inconvenience and requires the lifter to develop the habit of avoiding the 2 phantom gears.
The rest of the shifting is expected to be satisfactory due to the matching cable pull of 10-speed Campagnolo shifters and 8-speed Shimano shifters.
10-speed Campagnolo Shifter + 11-speed Shimano Derailleur + 10-speed Shimano Cassette
To explain why this combination is viable, it’s necessary to introduce another term known as cog pitch.
The cog pitch is the center to center distance between two adjacent cogs on a cassette.
The formula for calculating the cog pitch of a cassette is:
Cog pitch = Cable x Rear Shift Ratio
Note: The cog pitch also shows how much the derailleur moves per 1 shift
According to the formula, the cog pitch of a 10-speed Shimano road cassette is 2.3 x 1.7 = 3.91mm
An 11-speed road Shimano shifter has a 2.7mm cable pull which is extremely close to the 2.8mm cable pull of a 10-speed Campagnolo shifter.
Meanwhile, an 11-speed Shimano road derailleur has a rear shift ratio of 1.4 which is close to that of 9, 10 and, 11-speed Campagnolo derailleurs (1.5).
Thus, if a 10-speed Campagnolo shifter is combined with an 11-speed Shimano derailleur, the system becomes viable for a hypothetical cassette with a 2.8 x 1.4 = 3.92mm cog pitch.
A 10-speed Shimano cassette has a 3.91mm cog pitch (calculated above). Thus, the difference is only 0.01mm which is too little to break the combination.
Note: It’s also possible to use a 10-speed Tiagra 4700 derailleur instead of an 11-speed derailleur. Tiagra 4700 derailleurs are unique 10-speed derailleurs with an 11-speed ratio. In their core, the Tiagra 4700 series are an 11-speed system downgraded to 10-speeds.
9-speed Campagnolo Shifter + 11-speed Shimano Derailleur +9-speed Shimano Cassette
This case is very similar to the previous one.
A combination consisting of a 9-speed Campagnolo shifter and an 11-speed Shimano derailleur gives us a cog pitch of 3mm x 1.4 = 4.2mm.
Meanwhile, the cog pitch of an original 9-speed Shimano cassette is 2.5mm x 1.7 = 4.25mm.
Or in other words, the original 9-speed Shimano shifter will move the derailleur 0.05mm more. Since the difference is fairly small, a 9-speed Campagnolo shifter could offer a passable performance.
FAQ: What about using a Campagnolo shifter with a Shimano front derailleur?
In general, front derailleurs are more tolerant and create fewer chances of incompatibility because the jumps are larger and don’t have to be as refined.
Consequently, people have successfully combined front Campagnolo shifters with some Shimano front derailleurs. An older Shimano Ultegra front derailleur + Campagnolo Centaur shifters is one example combination known to offer satisfactory performance.
Ultimately, if the user already has a Campagnolo front shifter and a Shimano FD, it’s best to simply try the combination. The chances of success are quite high, although some adjustments could be necessary on occasion.