I wonder if there's any way to get a more traditional bar end shifter working. I can't stand twist grip shifters. I've got an Alfine rear hub with the Alfine thumb shifter, but surely someone should be clever enough to figure out a way to use something other than the twister.
Nice bike, though, I like the idea a lot, very clever way to get at this. And I'm not sure unless hell freezes over and I turn into some kind of racer that I'll ever buy another bike that has a derailleur, but I just can't see reaching down there and having to crank that thing for every gear change.
I've wondered about adapting the stem adapter with the twist grip but with some sort of fabricated lever attached to the twister to make it function more like an indexed downtube shifter. I don't know why, but those twist grips (my wife's bike has one) just drive me nuts.