We recently bought a used tandem and we are in the process of replacing some components. Being the captain on only a few rides so far, I find the need to steer, brake and shift to be a bit daunting ... but not impossible. The shifters are bar-end shifters and in order to change gears I need to take my hand off the handlebars and then fiddle with the lever position until I get the shift completed and the chain not "clicking". Doing a double shift is a long two-step process with more fiddling.
My wife, the stoker, seems to be in a better position to handle this task. I have two questions:
1) What are the downsides of stoker shifting vs. captain shifting from a team perspective. We need to communicate anyways. The stoker's view of the road is not perfect, but she can see the upcoming landscape (roadscape).
2) What kind of modifications would be needed for such a switch. I'd just move the same bar-ends to the rear and then I would need to get some mount-able shift-cable stops to keep the lines oriented correctly on the frame.