Member indian22 has built one, you should check out his build in the “old guys simplex...” thread. And he has done some serious road tripping on that build.
I’ve been considering building one using a planetary gear set, with two electric motors like a Toyota Prius power split device. Together with electronic ignition and throttle, it could all be controlled via a raspi from the throttle. I have the mechanical side handled, and I’ve got an idea of algorithms for the computer side. I can’t really say for certain how it’ll run because I need to do a lot more research.
But then every time I think about it, I think to myself that I could just put a much larger battery (ie... $2000) and an onboard Level 2 charger on my already fast ebike “worlds fastest schwinn” for simplicity. Problem is I’m limited to approx 1kw charge rate on the 110v plugs of local streets. I just don’t have the time or money to do it.
You kinda have to go at it with the question “what problem am I trying to solve?” And the best ways to go about it.