Don’t Do This With Campy Shifters

from Rookie’s keyboard,

Hello, friends

I hope your weekend is going well. Today, I am going to share with you a peculiarity of Campagnolo shifters that makes them a poor choice for non-Campy mech.

To understand why, you have to become familiar with the operation of index shifters. 

Modern bicycle shifters have “index points. “This means that the amplitude of the shifter is segmented into different sections. The shifter clicks to indicate a shift and inform the rider that a new section has been reached.

During the friction shifter era, it was up to the rider to decide how much to move the shifter for a shift to occur. But indexed bros don’t work like that. When set correctly, you just press a lever and the shifter pulls or releases a certain amount of cable to reposition the derailleur and trigger an upshift or a downshift. 

The amount of moved cable is known as cable pull and is pre-determined and non-changeable. (It varies on the number of speeds on the bike and the bike type – MTB/road).

The rear derailleur has a property known as the rear shift ratio(RSR).It indicates how much the derailleur moves per 1mm of cable pulled or released by the shifter. 

The values of the cable pull and the RSR determine how much the derailleur moves per 1 click. And since they depend on the number of gears, the brand, and the bike type, it’s not always possible to mix parts. 

But let’s get a bit more specific with a simple example.

The pull of 8-speed Campagnolo shifters is 3.5mm. 

The rear shift ratio of an 8-speed Campagnolo derailleur is 1.4. 

Consequently, each click moves the derailleur 4.9mm (3.5mm x 1.4).

Meanwhile, the cable pull of 11-speed Campagnolo shifters is 2.6mm. If an 11-speed shifter is used with an 8-speed derailleur, the derailleur will move 3.64mm (2.6mm x 1.4) per shift. 

The movement will be insufficient to move the chain to the desired cog.

Take away points:

If the cable pull of two indexed shifters is notably different, they cannot be used interchangeably. 

If the RSRs of two derailleurs differ greatly, the units aren’t interchangeable either.

Mixing Campy Shifters With Other Brands

To my awareness, indexed Campy shifters aren’t compatible with the widespread derailleurs of other brands such as Shimano when both are made for the same number of gears (e.g., combining an 8-speed shifter with an 8-speed derailleur).

And I have data to back this up.

Below is a table containing the cable pulls of Campagnolo and Shimano shifters. 

93.2mm (old), 3.0mm (new)2.5mm
102.8mm2.3mm (road), 3.4mm (MTB)
112.6mm2.7mm (road), 3.6mm (MTB)

The next table reveals the rear shift ratio of the respective Campagnolo and Shimano derailleurs:

91.4 (old), 1.5 (new)1.7
101.51.7 (road), 1.2 (MTB)
111.51.4 (road), 1.1 (MTB)

The data above indicates total incompatibility. But that is true only if you want to use a Campagnolo shifter to replace a Shimano shifter designed for the same number of gears.

But if we mix a shifter and a derailleur designed for a different number of speeds, a few semi-viable combinations appear.

Option 1:  

10-speed Campy 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. 

Therefore, if we focus on 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 original.

However, the combination will work only if the cassette is also an 8-speed model designed by Shimano.

If you use a 10-speed cassette, the derailleur will move too much.

An obvious issue is the fact that a 10-speed shifter has 2 more clicks. 

If the limit screw of the rear derailleur is not adjusted properly, the  10-speed shifter could throw the chain into the spokes or the frame and create an accident.

But if the limit screws are properly adjusted, the derailleur will be physically prevented from causing a similar scenario. 

The shifter will still have 2 “ghost” clicks, though. When the user shifts to speeds 9 and 10, the chain will not move. This creates an inconvenience and requires the lifter to develop the habit of avoiding the 2 extra gears.

The rest of the shifting performance is expected to be fine thanks to the matching cable pull of 10-speed Campagnolo shifters and 8-speed Shimano shifters.

Option 2: 

10-speed Campagnolo Shifter + 11-speed Shimano Derailleur + 10-speed Shimano Cassette

To understand why this combination is viable, you have to know what the term cog pitch means.

The cog pitch is the center-to-center distance between two adjacent cogs on a cassette.

The cog pitch of a cassette is calculated via the formula below:

Cog pitch = Cable x Rear Shift Ratio

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. The number is extremely close to the 2.8mm cable pull of a 10-speed Campagnolo shifter.

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).

Therefore, if a 10-speed Campy shifter is combined with an 11-speed Shimano derailleur, the combination is 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. The difference is only 0.01mm and is therefore too little to matter.

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. (The Tiagra 4700 series is an 11-speed system downgraded to 10-speeds.)

Option 3:

9-speed Campagnolo Shifter + 11-speed Shimano Derailleur +9-speed Shimano Cassette

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.

The cog pitch of an original 9-speed Shimano cassette is 2.5mm x 1.7 = 4.25mm.

The original 9-speed Shimano shifter would move the derailleur 0.05mm more. And since the difference is quite small, a 9-speed Campagnolo shifter could offer acceptable performance.

As you can see, it takes a lot of “science” to come up with viable options. And none of those are 100% foolproof. They are also a bit weird if we have to be honest. 

Personally, I wouldn’t bother mixing Campy shifters with derailleurs from other brands. It’s not worth the headache.

Until next time,

– Rookie






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