Originally Posted by
DiabloScott
I don't think so. Shimano 8, 9, and 10 are all compatible shifter/derailleur mech EXCEPT for DA8. So you could use any Shimano 9-speed shifter with any 8-speed cassette exDA.
No, all Shimano 8-speed cassettes have the same cog spacing. Dura-Ace 8-speed shifters and rear derailleurs are no cross-compatible with other groups. It just happens that the D-A shifter cable pull is the same as all Shimano 9-speed shifters (less one click). The 8-speed D-A rear derailleur has a unique actuation ratio. Read the info in the link I offered above. It's all there.