I have two bikes, both with grip shifters. Both of these required that I move my hand/wrist in the same direction to shift. Thus, to shift up a gear from say Second to Third gear, I rolled or moved my hand/wrist forward and away from my body. To shift down a gear from say Fifth to Fourth gear, I rolled my hand backwards and towards my body. This type of movement seemed natural and intuitive to me and I thought all bikes with grip shifters worked this way.
Then I recently got one of my bikes upgraded by my LBS from a 3 speed Shimano IGH to a 7 speed Shimano IGH. Now the 7 speed hub works in the opposite manner to what I described above. Thus, on this bike to shift up a gear from Sixth to Seventh gear I actually roll my hand backwards and towards my body and to shift down a gear from Fifth to Fourth, I roll my hand forwards and away from my body.
I was surprised that the upgraded bike came this way. I have gotten used to it by now after a few weeks but I have to think more about it when riding or else I will shift in the opposite direction I intend. I am also afraid that once I start switching more between both bikes I will have a harder time keeping them straight. Any experiences with this? Obviously not all bikes work the way I initially thought though. How do your grip shifters work?