My family bike, Xtravois, looks a little peculiar, but I’ve discovered recently that the frame design has some precedent in historical bikes, along with with the passenger-capable assisted longbike concept embodied in Xtracycles and my Stokemonkey product together.
At speeds above about 12 MPH, the biggest retarding force on a typical bicycle is wind resistance. Drafting other cyclists or more powerful vehicles is a good way to go faster, or to use less energy. Early in bicycling history, cyclists vying for speed records would draft tandem teams. Of course, this required a strong tandem team, and the better job they did at creating a wind break, the harder it was for them to keep ahead of the contestant. When suitable motors became available, some very interesting pace bikes came into being.
Notice the frame structures’ resemblance to my Xtravois design: an elongated mixte. Eventually the pacebikes became predominantly regular-wheelbase mopeds called Derny pacers.
So, one way to view an Xtracycle equipped with a Stokemonkey human-electric hybrid drive is as a revival of a historical pacebike design, bent to practical purpose: replacing car trips. The motors sure have gotten smaller!