The concept of drive-by-wire has taken over the automotive and motorcycle worlds in the last decade. The idea that there need not be a mechanical connection between the throttle and engine allowed the introduction of cutting-edge technology that enabled the fine-tuning of power delivery and throttle response. In the context of electric vehicles, drive-by-wire is at the very foundation—but what about electric bicycles?
I'm sure those of you who ride e-bikes have entertained the notion of a pedal-by-wire machine—one wherein the two-wheeler would no longer require a chain or drive belt. Well, it turns out that this could soon become a reality, as two German companies, Schaeffler and Heinzmann, have teamed up to make this a reality. In fact, the Free Drive system, as it's called, is now entering production.
A recent article by Electrek does an excellent job of highlighting the parallels between e-bikes and hybrid vehicles. In essence, all pedal-assist electric bicycles are in theory hybrids—parallel hybrids to be exact. It's precisely for this reason that folks like you and me have such confidence in e-bikes of today. On the one hand, you can manually pedal an e-bike even after it's run out of juice, and still make it home—eventually. Conversely, throttle-equipped e-bikes can also be ridden like an electric motorbike with no need for pedaling whatsoever—at least until it runs out of juice, at such point, you'll be left with nothing but your leg power and cardiovascular fortitude.
In the case of Schaeffler and Heinzmann's Free Drive system, the parallel hybrid system is gone, and the removal of a mechanical link between the rider and the rear wheel turns it into a series hybrid—meaning your pedal power and the electric motor are mutually exclusive. Herein lies the system's main drawback, well, at least in my opinion. You see, when the bike runs out of juice, no amount of pedaling can get you to your destination, leaving you stranded with a heavy, possibly expensive paperweight.
The way the Free Drive system works is with a power generator mounted within the bottom bracket. Sensors and controllers turn your legs' kinetic energy into electricity which then powers the motor on the back wheel. The concept is similar in nature to those flashlights you need to shake in order to build up enough electrical charge to power the bulb. Now, while there is indeed that drawback of potentially running out of juice, you could, in theory, pedal in place to bring the system back to life. Additionally, any excess energy produced from your pedaling effort can be channeled back into the battery.
In terms of practical applications, the Free Drive system seems to be best suited to cargo bikes, whose long wheelbase configuration could make it complicated to run a chain or belt drive. Indeed, in such applications, a system like this makes perfect sense. There is, however, the issue of balance and getting the bike moving from a stop, as the one-to-one connection between pedal and rear wheel is an integral part of getting rolling. Nevertheless, I'm more than certain that the folks behind the Free Drive system have come up with an ingenious solution for this.
Outside the world of cargo bikes, however, I'm not exactly certain that a system like this would be as effective. As a cyclist and e-bike user, I have the tendency to ride further than what my e-bike can handle. So yes, there have been multiple occasions wherein I've pedaled home with a dead battery. As such, the Free Drive system would certainly instill a whole new level of range anxiety in me—but hey, that's just me. What do you think about this new technology? Does it solve a non-existent problem, or is it the future of two-wheeled micro-mobility?