E-bike Riders Have Nothing to Lose but Their Chains

Bikes really haven't changed much since 1885, when John Kemp Starley sold the first Rover Safety Bicycle with a chain transferring power from the pedals to the rear wheel. E-bikes have worked pretty much the same way, with a motor and battery added.

Now Schaeffler, successor to the German company that perfected the ball bearing about the time when Starley was building his bike, has reinvented the idea of the bicycle with its chainless electric drive system called Free Drive.

The bike-by-wire system dispenses with the chain; pedaling turns a Schaeffler generator, which offers what feels like the right resistance as it absorbs the power from the rider, and then drives the Heintzmann 250 watt hub motor via a CAN (computer area network) connection. Any excess power is stored in the battery. The system is fully regenerative, charging the battery when going downhill or braking. There's no chain to break or get your pants stuck in, and there is no limit on how you design the bike.

“Regardless of whether the system is used in two-, three-, or four-wheel applications, the absence of a mechanical connection between the generator and motor means that Free Drive can provide maximum flexibility in the bicycle architecture and a freely configurable pedaling sensation, which is tailored to the requirements of the bicycle and the needs of the rider, while ensuring minimal wear,” says Dr. Jochen Schröder, president of the Schaeffler E-Mobility Division.

Basically, you can design an e-bike or trike without having any kind of link between the pedals and the motor other than a wire that you can route anywhere. There are other benefits: "Free Drive offers an ergonomic, low maintenance, and robust system with low operating and maintenance costs, as wear parts and peripheral chain equipment are not required."

The genius of John Kemp Starley's design was that the wheels on his bike could be the same size, since the big gear with the pedals could drive the smaller rear gear faster. That's why it was called a safety bicycle; riders were no longer perching on top of a big wheel with direct drive. But it does have its limitations when you try to design a cargo bike, when the chain is often connected to shafts or other complicated methods of getting power to wheels that don't line up with pedals.

When Rob Cotter designed the ELF electric trike he had to have a big CVT (continuously variable transmission) and a very long chain to get the pedals to work together with the motor. It would have been so much easier with this.

This is not the first time we have seen this idea on Treehugger; Derek Markham wrote about the Hybrid Module Mobility concept from Mando in 2017. That never rolled off the line, but it did demonstrate the flexibility of the system; you can put the rider/driver and seat anywhere—front, back, or middle. Markham also linked to a post by Kris de Decker in Low Tech Magazine, who writes that "generating electricity is far from the most efficient way to apply pedal power, due to the internal energy losses in the battery, the battery management system, other electronic parts, and the motor/generator." Schaeffler admits to Micah Toll of Electrek that it is 5% less efficient than a direct chain connection, but that might well be compensated for with lighter weight and a different design.

The decoupling of the pedals from the drive on an e-bike will create interesting opportunities; we can probably expect to see some wild new designs for cargo bikes in the next few years.