The German company Schaeffler revealed a new and innovative driving system for electric pedal-powered bicycles that avoids traditional bicycle chains and belts for a fully electric system. The new system is known as Schaeffler Free Drive. It was developed jointly with electric bike transmission specialists Heinzmann. It relies on a generator installed on the lower rack of the bike. The pedal movement by the passenger operates the generator and converts energy from mechanical energy to electrical energy. This eliminates the need for any form of mechanical power delivery to the rear wheel, such as chains or belts.
This energy is delivered to the rear wheel via cables installed inside or outside the bike frame, rather than being sent mechanically via a chain, and is converted back into mechanical energy to propel the bike forward. This wired bike system is controlled by CAN connections between the motor, battery, alternator, and control electronics, and the alternator can change the resistance in the pedals based on the amount of pedal effort required or chosen.
If the rider is pedaling hard enough to generate excess power (more than is required to run the engine at the current speed), that energy is discharged into the electric bike's battery for later use. The rear motor is also capable of regenerative braking, which provides another way to charge the battery while driving, and the motor comes with a power of 250 watts. Although this may seem like a very complicated system for conventional electric bikes, the benefits of non-traditional electric bikes cannot be underestimated.
Drive systems for electric bikes to transport goods, especially those with three or even four wheels, can become complex and costly when operated by traditional mechanical means. But the bike-by-wire system allows electric bike designers to get more creative in bike design.
They will no longer be limited to designing around the long-chain or multi-stage reduction gears. Instead, they can design based on the vehicle's needs and steer the electrical system around the tire as necessary. In addition, the new drive system allows riders to charge the electric bike's battery when pedaling.
But one of the main downsides to the setup is the low pedal efficiency. A Schaeffler representative explained that the Schaeffler Free Drive is approximately 5% less efficient than series drives.
As he explained, this means that the rider would need either a 5% larger battery to get the same distance or experience a 5% shorter range compared to the same chain-engine bike.