Originally Posted by
jgwilliams
If you don't want to change the rear derailleur then you need to find the pull ratio and get some shifters that match. The pull ratio is a measurement of how much cable is pulled for a given movement of the derailleur. Unfortunately manufacturers love to mess with the ratio from one year to the next - ostensibly to improve performance. As long as the shifter pull ratio matches that of the derailleur then it will work. The same is true for the front derailleur, of course, but it's not quite so critical.
Shimano 9sp was, as far as I can recall, compatible across the range and from MTB to road bikes. A set of 9sp Shimano mtb shifters will index perfectly with 9sp road parts.
The front derailleurs from that era, though, were not cross-compatible between MTB and RB.