# Early Campagnolo Chorus rear derailleur index shifting



## Squidward (Dec 18, 2005)

*History lesson*
Back in the day, before Indexed shifting, Shimano derailleurs were different than what we know today. The parallelogram pivots are perpendicular to the upper and lower pivots, the lower pivot is inline with the parallelogram, and the upper pivot is spring loaded like the lower pivot. This allowed the upper pulley to track the angle of the cassette. Suntour rear derailleurs were different. They had their slant parallelogram system where the parallelogram pivots were at an angle compared to Shimano pivots, allowing the derailleur cage to track the angle of cassette. I cannot recall if the upper pivot was locked into position or spring loaded or free to move without spring assistance. The lower pivot was offset just like the upper pivot. Campagnolo rear derailleurs were completely different from what today’s rear derailleurs look like.

This is all from memory so I may have some details wrong here.

Today’s indexing rear derailleurs all pretty much look and work the same, no matter if it comes from Shimano, Campagnolo, or SRAM. The critical difference between them is the shift ratio, the amount the derailleur cage moves over for each millimeter of cable pulled.

*My Chorus rear derailleur*
I bought a frame, forks, and most of a mixed Campagnolo Chorus/Athena gruppo from a friend that came with this 1989 (or thereabouts) rear derailleur. The shifters and headset are Athena and the rest are Chorus, from what I was told. He threw in a Dura-Ace 6-speed corncob freewheel that he said worked beautifully with this combination of shifters and rear derailleur. When I assembled the components into a working bike I found the shifting to be vague and imprecise.

The rear derailleur I picked up is an early Chorus component that has what I’ve heard described as A/B settings. The parallelogram is adjustable so that it can either emulate pre-indexing Shimano or Suntour derailleurs. You can see in the picture the indexing mark and the A and B that you can set the derailleur to. In the A position the rear derailleur emulates the Suntour system. In the B position the derailleur emulates the Shimano system (albeit without the spring-loaded upper pivot, though this one is free to rotate). Obviously, in the A position the rear derailleur has a relatively high ratio of about 3. In the B position the ratio is closer to 1.9 due to the parallelogram traveling downwards as it moves sideways.

Trying to get this derailleur to index shift has been a pain in the rear for me. I have tried out a few combinations of shifters with this derailleur to try to get this to index decently. The only reason I decided not to run a freewheel was that corncob: I ride on hills all the time. I have only tried this derailleur with Shimano cassettes as I have quite a few different combinations (7, 8, 9, and 10-speeds, 5mm, 4.8mm, 4.35mm, and 3.95mm, respectively). I only have one Campagnolo cassette, a 10-speed.

Here are the combinations that I have found to work relatively well. I have included pictures of the derailleur and the shifters.

Campagnolo Chorus derailleur in B mode, conventional cable routing (behind the bolt), Suntour GPX downtube shifters in 6-speed mode (it has enough clicks to accommodate 10 speeds in this mode before the lever has lain itself onto the derailleur cable – in 7-speed mode it will accommodate as much as 11 speeds), Shimano 7 or 8-speed cassette (5mm gear spacing). This combination works beautifully with nice, solid shifts from the shifters and crisp shifts into each gear in either direction, pedaling while I shift or not.

Campagnolo Chorus derailleur in A mode, conventional cable routing, Campagnolo Chorus 7-speed downtube shifters, Shimano 7-speed cassette (I tried an 8-speed cassette but the shifter would pull back into the seventh position when I let go of it). This combination works well enough but without the crispness of the Suntour shifters and you have to hold the lever at the end of the shifter play in order for it to shift to the next gear.

Campagnolo Chorus derailleur in B mode, conventional cable routing, Campagnolo Centaur 10-speed brifters, Shimano 7-speed cassette. This combination worked well enough for the first six gears then one extra click before the last gear.

Campagnolo Chorus derailleur in B mode, alternate cable routing (cable in front of the bolt), Campagnolo Chorus 7-speed downtube shifters, Shimano 9-speed cassette. This combination shifts well until you reach the last click then you have to friction shift the last two gears. I have not tried riding with this combination, I only ran through the gears on the bench. This is the combination that I plan to run on my neo-retro setup.

Anyone else tried this derailleur and got it to index properly?


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## bigbill (Feb 15, 2005)

It is fun to see what works. I rode with a guy back in 1989 who used dura ace 7 speed indexing with a campy victory rear derailleur. Apparently the stuff indexed well. He could have used a dura ace rear derailleur, but he wanted to be different.


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## Mark McM (Jun 18, 2005)

*Derailleur design*



Squidward said:


> Back in the day, before Indexed shifting, Shimano derailleurs were different than what we know today. The parallelogram pivots are perpendicular to the upper and lower pivots, the lower pivot is inline with the parallelogram, and the upper pivot is spring loaded like the lower pivot. This allowed the upper pulley to track the angle of the cassette.


Yes, this is good description of how Shimano derailleurs were designed. The two spring pivot system was originally developed by Simplex (all derailleurs before that used only one spring pivot). The drop-parallelogram (parallelogram below the upper pivot) was also in use before Shimano adopted it.



Squidward said:


> Suntour rear derailleurs were different. They had their slant parallelogram system where the parallelogram pivots were at an angle compared to Shimano pivots, allowing the derailleur cage to track the angle of cassette. I cannot recall if the upper pivot was locked into position or spring loaded or free to move without spring assistance. The lower pivot was offset just like the upper pivot.


The slant parallogram was patented by Suntour, and no one else used it until the patent expired (expired in the mid-'80s). None of Suntour's road derailleurs had a true top spring pivot, and instead relied on the parallogram to track the cassette (some versions had a weak spring in the top pivot whose only function was to pull the derailleur out of the way when the wheel was removed/installed, but this spring was too weak to actuate in actual usage, and the derailleur remained at a constant angle in use). Later Suntour MTB derailleurs ('90s) had a true double spring pivot, just like Shimano (Campagnolo also adopted the double spring pivot around the same time).



Squidward said:


> Campagnolo rear derailleurs were completely different from what today’s rear derailleurs look like.


Campagnolo from that era used a single spring pivot (the cage pivot), and for most models the parallogram went straight from the hanger bolt to the cage pivot. However, later Rally models used a dropped parallelogram (like Shimano), but with only a single spring pivot.



Squidward said:


> Today’s indexing rear derailleurs all pretty much look and work the same, no matter if it comes from Shimano, Campagnolo, or SRAM.


Yes, except for the occasional slant plunger type derailleur showing up now again (Mavic Zapp and Mektronic, White Brothers LMDS), all derailleurs for the last 15 years have been dual spring pivot slant parallelogram models.



Squidward said:


> The rear derailleur I picked up is an early Chorus component that has what I’ve heard described as A/B settings. The parallelogram is adjustable so that it can either emulate pre-indexing Shimano or Suntour derailleurs. You can see in the picture the indexing mark and the A and B that you can set the derailleur to. In the A position the rear derailleur emulates the Suntour system. In the B position the derailleur emulates the Shimano system (albeit without the spring-loaded upper pivot, though this one is free to rotate). Obviously, in the A position the rear derailleur has a relatively high ratio of about 3. In the B position the ratio is closer to 1.9 due to the parallelogram traveling downwards as it moves sideways.


If I recall correctly, even in the A position, there is still a small angle to the parallelogram. The ideas was that the angle could be changed to match the cassette - a narrow range cassette would use the A (less angled) position, and wide range cassette would use the B (more angled) position. This derailleur was around during Campagnolo's first attempt at indexed shifting (called Syncro) which used interchangeable indexing disks to match the shifter the derailleur/freewheel combination, but I don't recall if a different shifting disk was to be used for the different positions.


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## Squidward (Dec 18, 2005)

Mark McM said:


> This derailleur was around during Campagnolo's first attempt at indexed shifting (called Syncro) which used interchangeable indexing disks to match the shifter the derailleur/freewheel combination, but I don't recall if a different shifting disk was to be used for the different positions.


Thanks for the info, Mark. I believe that I remember seeing an A and 7-speed on the indexing ring. I wonder if there is a source for these?


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## JacekPoc (Feb 18, 2018)

I'm a new and inexperienced campy fan wishing to say hello.


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