One of my criteria when I built the Electrom was that I wanted to be able to use it to get my mountain bike to our local off-road riding areas. I live in Victoria BC, and sadly, while we have some of the best off-road cyclists in Canada living and training here, our city has not seen fit to allow riding in any of the local parks. As a result we have to put our bikes in vehicles and drive half an hour to ride. I know that doesn’t seem like a big deal, but I just can’t get used to the idea of driving a car to ride my bike. I could get an electric MTB going I guess, but for some reason I still prefer legs-only power for off road.
So, enter the bike-tow system for my electric machine. I’ve fashioned a quick install mount that receives the front axle of my Norco Sight mtb. To install it I simply take out one of my tail-box mounting bolts and fasten the bike-tow with a slightly longer bolt. It takes only a minute to install. Then I can attach the front fork of the mtb, strap the front tire on, and go. It works really well.
you could make a similar system that could fasten to a rear-rack on an upright bike.