Originally Posted by SkyDog75

He meant that some Shimano 9-speed left shifters were meant for use on both double and triple drivetrains. If you had 105 5500-series shifters, for example, you’d use the same shifters — and thus the same part numbers — whether your bike was a double or triple.



On those shifters that were intended for either double or triple drivetrains, I suspect that maybe the detent/trim positions were different. Someone who’s ridden them can hopefully confirm.