New ‘pedal-by-wire’ drivetrain allows you to unchain your e-bike

23 Feb 2023

Tired of having to fiddle about and clean the chain on your electric bike? Well, you might not have to: two German firms have teamed up to develop the first chainless drive system for e-bikes.

The new system is called Free Drive, and has been developed by engineering giant Schaeffler and bike drivetrain specialist Heinzmann. Focused particularly on cargo e-bkes, the system was first shown in concept form in late 2021, and series production has now started.

So how exactly does a bike work if there isn’t a chain linking the pedals and the rear wheel? It’s all down two an electronic pedal-by-wire system, replacing the physical link with digital technology.

The ‘hybrid’ Free Drive system consists of a pedal generator, a drive motor, a battery and a human machine interface (HMI). The key component here is the Schaeffler-developed pedal generator. Instead of turning a cog that winds a chain, turning the pedals produces resistance that it used to provide electricity to the motor in the rear-wheel hub. 

The motor can deliver a total output of 250 watts – that’s the same as the maximum power allowed on UK-standard pedal assist e-bikes – and any surplus electrical energy generated by furious fast pedalling is used to charge up the bike’s battery.

Because of the lack of a physical connection, the firms claim that turning the pedals requires less muscle power than a conventional e-bike drivetrain, which is particularly useful for cargo e-bike riders tackling long journeys with heavy loads.

To be clear, this isn’t like some of the wild high-powered e-bikes available outside the UK that feature motorbike-style throttles: the hybrid system still uses pedal power to drive the wheels. The difference is that the power you generate is sent to the wheels as electricity through a wire rather than on a chain. That’s significant, because it means the machine should still meet UK e-bike rules.

Heinzmann is responsible for selling the complete Free Drive unit to bike firms and fleet operators, while Schaeffler is contributing the pedal generator.

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The two firms claim that one key benefit of the Free Drive system is that it, because it doesn’t need a chain, belt, gear rings or sprockets, it is less prone to mechanical wear than a conventional system. It also allows for gear shifts and different drive modes to be controlled by software.

The system has bigger potential, too: the design of conventional e-bikes is dictated by the need for the mechanical connection between the pedals and the motor, so a pedal-by-wire system opens up considerable design freedom.

Jochen Schröder, the head of Schaeffler’s e-mobility division, said the system “opens up completely new possibilities in bike architecture and pedal configuration – including designs with two, three or four wheels, with or without a roof.”

The first customer for the Free Drive system is German firm CIP Mobility, which is installing them on its new Mocci Smart Pedal Vehicles, a cargo e-bike designed to tackle urban deliveries.

The Mocci features an integrated software system that allows the ride to be customised to the needs of each firm and rider, while its key structural components are made from recyclable high-performance plastic, which the firm claims creates 68 per cent fewer CO2 emissions to produce than an aluminium frame.

Schaeffler and Heinzmann are looking for further customers for the Free Drive system, with plans to steadily increase capacity in the coming years.

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