Can a Athena 8spd shortcage RD be use on 9spd ergoshifters?

Thanks
Rick

If it is the newer 9 speed the answer is yes if you change to the thinner 9 speed jockey wheels and shorter 9 speed jockey wheel bolts (may work okay even with the 8 speed jockey wheels).

If it is the older 9 speed then the answer is no. The geometry of the old 9 speed was different than the 8 speed. The new 9 speed deraileur works with 8 speed shifters and the 8 speed derailuer works with the new 9 speed shifters, but the 8 speed will not work with the old 9 speed shifters. You can get a new 9 speed shifter cog for the ergo shifter, but they are quite tricky to install and cost about $20 and Branford. At that point you might as well get a 9 speed derailuer