Originally Posted by
billridesbikes
As I recall the 8sp Campagnolo cassette had the same spacing as an 8sp Shimano cassette or it was super close that you could switch rear wheels during a race with the other without too much adjustment.
But you still need the 8sp levers, and I think you'll find old 8sp Campagnolo Ergo power levers and old 8sp Shimano STI levers to be about the same price.
Campy 8 and Shimano 7 (not 8) had the same
cassette spacing. This is fine for switching wheels, but the cable pull of the shifters is not even close. Campy pulls a lot more cable.
Campy 8: 3.5mm per click
Shimano 7: 2.9mm per click
Shimano 8: 2.8mm per click
Campy 10: 2.8mm per click
You cannot use a Shimano 8 shifter to index a Campy 8 drivetrain (unless there's a Shift Mate for that combination.)
P.S. I included Campy 10 because it happens to have the same cable pull as Shimano 8, which means you CAN put a Campy 10 shifter on an otherwise Shimano 8 drivetrain and it will shift perfectly. I've done this many times.