Originally Posted by
CliffordK
The other option to do 9s Campy on 9s Shimano cassettes is:
"Late Model" 9s shifters +
"Early Model" 9s derailleur (or most 8s derailleurs)
And the cable pull should be just about exact.
Campagnolo 11s shifters are also supposed to work reasonably well with older Shimano STI derailleurs to shift 9s (limited to 9 sprockets).
Thank you: you know your stuff. Late model 9-speed shifters pull 3.0 mm of cable per click. The early 9 speed (and 8-speed) Campy derailleurs have a mechanical advantage of 1.43. 3.0 x 1.43 = Shimano 9-speed cog spacing.
A happy outcome. The math works, and it works in practice.