A radical new “ride-by-wire” system replaces e-bike chains and belts

German company Schaeffler has just unveiled an innovative new drive system for e-bikes that eschews traditional bike chains and belts for an all-electric system. The new system is known as Schaeffler Free Drive and marks the entry of one of the most divergent e-bike drivetrains we’ve seen in years.

The Free Drive, which was co-developed with e-bike drivetrain specialists Heinzmann, is based on a generator fitted to the bike’s bottom bracket.

The cyclist’s pedaling action powers the generator and converts mechanical energy into electrical energy.

This eliminates the need for any form of mechanical power transmission to the rear wheel, such as chains, belts or drive shafts.

Instead, electricity is sent to the rear wheel motor, where it is converted back into mechanical energy to propel the bike forward. This “bike-by-wire” system is entirely controlled by CAN communications between the engine, battery, generator and control electronics.

The generator is able to vary the resistance of the pedals according to the pedaling effort required or selected. If the rider pedals hard enough to create excess energy (more than is needed to power the motor at the current speed), that energy is dumped into the e-bike battery for later use.

The rear motor is also capable of regenerative braking, which provides another way to recharge the battery while driving.

pedal generator

The motor isn’t particularly powerful at just 250W, although that’s the European limit for e-bike motors in Germany. This drive is designed for pedal-assist riding, not high-powered throttle e-bike riding, so can make do with a smaller motor than we see on many e-bikes in North America .

While this may seem like an overly complicated system for conventional e-bikes that unnecessarily reinvents the wheel (pun shamelessly), its benefits for unconventional e-bikes cannot be ignored.

Drive systems for cargo e-bikes, especially those with three or even four wheels, can become complicated and expensive when powered by traditional mechanical means. But a bike-by-wire system would allow cargo e-bike designers more creativity in bike layout.

They would no longer be forced to design around a long swinging chain or multi-stage gear reductions with drive shafts and derailleurs.

Instead, they can design around the needs of the vehicle and simply route the electrical system around the chassis if needed.

In addition, the new training system would allow runners to finally answer “Yes!” to one of the most common (and ill-informed) questions from passers-by seeing an e-bike for the first time: “Does it charge while you pedal?” »

One of the main drawbacks of the setup is reduced pedaling efficiency. Chains are still the most efficient way to power a bike and belt drives offer only a slight loss in efficiency.

A Schaeffler representative explained to Electrek that the Free Drive is about 5% less efficient than chain drives.

As he explained, this means the rider would either need a 5% larger battery to get the same distance, or a 5% shorter range compared to the same bike with chain drive.

But efficiency wasn’t the team’s main focus, and they consider the slight drop in efficiency to be worth it, i.e. the increased design freedom that should open the door to countless opportunities for the interesting construction of e-bikes.

Schaeffer will showcase the Free Drive at the Eurobike 2021 show in Friedrichshafen, Germany. It will be located at the stand of their business partner, Heinzmann.

We’ll be sure to check it out for you, but until then, we want to know what you think of Free Drive. Let us know in the comments section below!

Image credits: Schaeffler

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