Chainless bike drive
Dmitrii Blium
News
German company Schaeffler has just revealed an innovative new drive system for electric bicycles that replaces traditional bike chains and belts with an entirely electrical-driven system.
Technology
The Free Drive system was co-developed with electric bicycle drivetrain specialists Heinzmann. The base of the system is a generator installed at the bike bottom bracket.
The pedaling powers the generator and converts the energy from mechanical to electrical energy. That removes the need for any form of mechanical power delivery to the rear wheel, such as chains, belts, or driveshafts.
Instead, the electricity goes to the motor in the rear wheel. There it is converted back into mechanical energy to power the bike forwards. CAN (Controller Area Network) communications between the motor, battery, generator, and control electronics control this “bike-by-wire” system.
The generator varies the resistance in the pedals based on how much pedaling effort is required or selected. Excess energy goes into the e-bike’s battery.
The rear motor can also regenerate energy from braking, which offers one more way to charge the battery while driving.
The motor has just 250W, though that is the local limit for electric bicycle motors in Germany. Besides, this drive is for pedal-assist riding, not high power throttle e-bike riding.
Application
You may argue that all this might sound like an overly complicated system for conventional electric bicycles. However, you cannot discount its benefits for non-conventional e-bikes.
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 laying out the bike.
No longer would they be constrained to design around a long, flapping chain or multi-stage gear reductions with jackshafts and derailleurs.
Instead, they can design based on the vehicle's needs and route the electrical system around the frame as necessary.
Plus, the new drive system would allow riders to finally answer “Yes!” to one of the most common (and misinformed) questions from passersby seeing an e-bike for the first time: “Does it charge when you pedal it?”
💡 Article on Electrek