Originally Posted by
bullwinkle
I may be missing something here, but I don't think so. I know the spacing of Shimano cogs is different from Campy, but its the shifters that cause the RD to move the required distance. I.e., the RD will do whatever the shifter tells it to do. Thus, as long as the shifter is Campy (to match the Campy cogs), everything should be cool. Right?
Wrong. Rear derailleurs are typically compatible only within a given manufacturer's line. Most Shimano rear derailleurs will work with any of Shimano's shifters and cassettes no matter what the number of "speeds". Campy is the same in that current Campy shifters will work with any current Campy derailleur and cassettes.
However, that doesn't mean that a Campy shifter will work with a Shimano rear derailleur even if you use a Campy cassette and, in fact, it won't unless you use a converter such as a Jtek Shiftmate.