This is C&V in the sense that it can extend the usage of your parts bin, and the Shimergo topic has been discussed here before...

As part of migrating my 2013 Super Record group to a most non-C&V frame, I sprang for the latest Potenza group for my KOF custom steel bike. Knowing that Campy changed the shift ratio for their SR through Potenza level stuff starting in 2015, and not finding much on the interweb about possible new mix and matching options...

My stand tests show that using a Potenza RD with 10 speed Veloce controls shifts through a Shimano 10s cassette flawlessly. Looks like older 11s Athena brifters should be able to use a Potenza RD to shift perfectly across a Shimano 11 speed cassette also (will test that when I get the Potenza brifters on my KOF frame). The shift ratio of the new campy RD is around 1.43 whereas the 8 speed era Campy was 1.42 (close enough for some interesting possibilities there also).

My calculations also indicate that the cable pull of Potenza 11s brifters is nearly identical to Shimano 11 brifters (2.7mm per click). This should allow you to swap in cheaper and lighter "new" Campy 11 brifters into an otherwise Shimano 11s drivetrain. Good news since the campy hoods are nicer imo and I prefer campy thumb controls for going to smaller cassette cogs.

Just some findings from my subterranean bike appreciation zone.

Thanks for sharing!

I've got a bike that's using an "old 9 speed" (1.4) Racing T rear derailleur with a 10-speed Record shifter to shift a 10-speed Shimano cassette. I had a discussion not long ago on the mechanics board where someone couldn't understand why I was excited to have a use like this for an obsolete derailleur. Maybe he'd have been more impressed to see the same trick with a Potenza RD.

I have a Sachs New Success RD that I got from Dfrost and I'm hoping/suspecting that it also has the 1.4-ish shift ratio. I have some 2002 Centaur 10-speed shifters that I bought specifically to try this out but I haven't found time for it yet. It's good to know that a new Potenza RD will serve as a workable Plan B.

I’ve suspected for a while that the 11 speed stuff is compatible but hadn’t heard of anyone trying it.