Message:
>Is the new XTR rear derailleur RD-960 SGS compatitable with XT Rapid Fire shifters? I have attempted to install this rear derailleur without success. Any advice is helpful.>Thanks
When you say "compatible" I presume you mostly want to know if your XTR RD-960 rear derailleur will INDEX properly with an older Shimano shifter (M-750?). The short answer is "YES."
I am stating the obvious, but bare with me ...
The newer RD-960 is what Shimano formerly referred to as REVERSE-PULL -- meaning that when the shifter was NOT applying any tension to the derailleur cable, the cage will position the pulley over the LARGEST (most inboard) cog instead of the smallest (most outboard) cog.
I suspect that the difficulty you may be experiencing is due to not having your stops adjusted properly and/or __?__.
Hope that helps. If not, describe your problem, further.