It is not often that we see a complete redesign of a drivetrain, and innovation is usually approached within the standard chain and derailleur configuration that has existed since the birth of gear bikes. CeramicSpeed, however, is attempting to break the mold with its Driven concept drivetrain.

CeramicSpeed introduced the Driven concept just over a year ago, making bold claims of 99% efficiency and other advantages over standard drivetrains. However, this first example was not rideable. It did not have a gear change mechanism and was limited to road bikes.

This year, Thermic Speed worked with the University of Colorado's Department of Mechanical Engineering to launch its latest version, which answers three big questions.

The Driven uses a dual pinion configuration with a front fixed pinion and rear split pinion for gear shifting. The pinion consists of a ring of CeramicSpeed bearings, forming a meshing method.

Gear shifting is wireless, with the shifting mechanism, actuator, and rechargeable battery housed within a hollow carbon shaft. By splitting the rear pinion, each half can move independently in a gear change that CeramicSpeed describes as a "step-and-follow pattern."

During the gear change, the lead half of the pinion moves to a new gear position when it is disconnected from the cassette. The subsequent half that is disconnected from the cassette then completes the gear change. This can be compared to a dual-clutch system in an automobile, since the drive train is not disconnected during a gear change.The Driven system can shift to any point on the cassette, and the self-aligning decoupler system allows a single mechanical movement to Multiple gears can be changed. CeramicSpeed claims that this allows for seamless gear changes with shifting speeds that outperform conventional electric drivetrains

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Understanding this system can be daunting, so CeramicSpeed has released a video explaining how it works.

CeramicSpeed has begun rider load testing with a single-speed version of Driven at the velodrome, and testing appears to be ongoing. They also recently visited Specialized's "WinTunnel" wind tunnel facility and claimed that the Driven is the most aerodynamic drivetrain ever tested.

When the first prototype was presented, the Driven was quickly dismissed as a road bike-only concept due to the varying effective chainstay lengths of full suspension mountain bikes. CeramicSpeed is a new aerodynamic drivetrain that, during suspension compression, follows the trajectory of the rear wheel It addressed this problem by using telescopic shafts that move and extend along the trajectory of the rear wheel during suspension compression.

While drivetrain efficiency and aerodynamics are less important on mountain bikes, shaft drives have other advantages. By freeing the rear suspension from the effects of chain forces, the suspension works more effectively and the system is more compact, reducing the risk of damage from trail strikes.

With systems that use such high tolerances, there is much debate regarding the durability of the system. Valid questions regarding shifting under load, durability, deflection in real-world driving, and ability to handle dirt have yet to be answered. However, at this proof-of-concept stage, these hurdles are not of much concern and are points that CeramicSpeed will address as it continues to develop.

It will be exciting to see examples of Driven on bikes as development progresses, but Driven is still a concept, and until a real-world test model is unveiled, it will be difficult to tell if this drivetrain will be as good as the old faithful derailleur or pinion P-Line Until a real world test model is shown, it is very difficult to speculate how this drivetrain will compare to other drivetrain approaches such as the old faithful derailleurs or pinion P-Line. However, it is clear that this unique drivetrain is a step in the right direction.