Might a Campy 12 rear derailleur be "compatible" with 10 speed?

[donevwil]

I need a medium cage rear derailleur for a C10 drivetrain and know an 11 spd unit would work fine, but what about a 12 spd piece? The revised geometry is intriguing and they can be found for less than 11 spd.

[ultraman6970]

11 rd will work with 10? models in specific?

[donevwil]

I've personally used an older Athena, but according to the brain trust here they all work regardless of the minor pull change in the more recent ones.

I'm unaware if 12 is a wholesale change in pull and chain clearance, too many generations ahead of my current existence.

[Dave]

Not likely. 10 and 11 speed RDs are not compatible. I modified a 10 speed RD to work with early model 11, but late model 11 speed shifters pull more cable.

I've got a device to accurately measure cable pulls, I've never used it with my 12 speed bikes.

10 speed parts are now so old that I don't see the point. Move on to 12 and get it over with.

I switched two bikes from 11 to 12 in July and have no regrets. I got enough from the old parts (many 2018) to make it worth it. I really needed the new 48/32 and 11-34.

[oldpotatoe]

11 rd will work with 10? models in specific?

Any. I’ve used a 11s rear der onto 10s ERGO more than once, works great.

[dddd]

10 and 11s Campag rear derailers had the same actuation until 2015.

I've used a nearly current 11s Chorus RD on an older 11s bike and did a bit of cable anchor modification to make it work a little better than sort of ok. It wasn't my idea, but I had to deal with it during the install of a larger cogset for a gentleman in his 80's.

[jtbadge]

Good luck, half of 11s Campy is not even compatible with the rest of 11s. Genius!

[dddd]

Good luck, half of 11s Campy is not even compatible with the rest of 11s. Genius!

It seems that their re-design to accommodate larger cogs somehow precluded staying with the existing actuation ratio(?).

So in effect, the pre-2015 shifters (if not the entire mini-gruppo) have been rendered obsolete, at least for those wanting today's fashionable wide-ranging gear ratio.
Even simply finding an actual replacement pre-2015 rear derailer can involve more work and/or cost than expected, if one happens to damage theirs.

[oldpotatoe]

Good luck, half of 11s Campy is not even compatible with the rest of 11s. Genius!

Also not true..2015 rear ders will work with pre 2015 shifters and vice versa. For above as well..What DOESN'T work is 10s rear ders with 11s shifters..but the opposite is fine and dandy.
Altho a YUGE Campag fan-boy(surprise!!), I take a lot of what the big boys in Italia say about inter-compatibility with a granello di sale...

AS far as 12s..don't know. I'd try it but no longer in the trenches.

[ultraman6970]

Ok then 11 rd's work with 10 speed shifters...

And any generation rd 11 will work with 11 shifters...

Those are great news.

[Dave]

I've precisely measured the cable pulls of the early and late model 11 speed shifters and know for certain that they are not the same. I can post the cable pull for each shift, if desired. I connected the shift cables to a 2 inch travel dial indicator that registers in .001 inch increments.

When 11 speed first came out, I hooked a 10 speed RD to the shifters and found that the RD only traveled about half way between the last two sprockets after all 10 shifts. To make it work much better, I ground the threads down to the root, where the cable contacts the clamp bolt, to shorten the lever arm length and increase the total travel. The same trick works when using a newer model 11 speed RD with the older shifters.

[oldpotatoe]

I've precisely measured the cable pulls of the early and late model 11 speed shifters and know for certain that they are not the same. I can post the cable pull for each shift, if desired. I connected the shift cables to a 2 inch travel dial indicator that registers in .001 inch increments.

When 11 speed first came out, I hooked a 10 speed RD to the shifters and found that the RD only traveled about half way between the last two sprockets after all 10 shifts. To make it work much better, I ground the threads down to the root, where the cable contacts the clamp bolt, to shorten the lever arm length and increase the total travel. The same trick works when using a newer model 11 speed RD with the older shifters.

I agree they aren't the same but I have put 11s ders onto 10s ERGO systems and they worked great. Just my experience.

[Ralph]

Pre 2015 11's, especially Athena, work great with 10's levers. Athena 11 is a direct replacement.

[FlashUNC]

All the changes they made with Rev+ and now 12 speed would lead me to believe it may work great out of the box and for a few months, but long term the differences in tolerance and cable pull will lead to more finicky, less reliable shifting and possibly more wear too.

I'd just get a new shifty bits -- derailleurs and levers, keep the crank and call it a day.