Ceramicspeed has just invented the world’s fastest bicycle drive-train. The concept drive train removes the chain and rear derailleur and cassette cluster, and replaces 8 points of sliding friction with 2 points of rolling friction, where the ceramic ball bearings engage the teeth.
“A revolutionary drivetrain concept that sets new standards in efficiency and eliminates the need for derailleurs and chains”
Ever since 1920s, the advancements in the bicycle drivetrain technology have been evolutionary rather than revolutionary. Driven bike from Ceramicspeed innovates the drivetrain design by challenging conventional design using a chain and derailleur. The project was started by Ceramicspeed with the pursuit of one percent in order to improve the efficiency of the traditional drive-train by 99%. The traditional drive-train could not be optimized in its original configuration. The objective was to get power from rotational front axis and rotational rear axis with only one percent power loss. Ceramicspeed teamed up with University of Colorado mechanical engineering department to come up with a design that was simplest design with most efficiency.
How does it work
The bearing are ceramic and they interface with the teeth and the bearings actually roll through the teeth. This creates zero sliding friction and the bearing is actually index so there is slight amount of rolling friction with each bearing as it engages. However, two points of rolling friction is much less than eight points of sliding friction in a traditional drive-train. This is the biggest advantage and as far as the numbers go, the new system creates forty nine percent less friction than a standard derailleur style setup.
One of the benefits of a chainless drive-train is that it is much lighter than a traditional chain derailleur. Ceramicspeed removed the chain and rear derailleur assembly, mechanics, cage, and the cassette, which was replace with a relatively light weight carbon fiber shaft and pinions and a very thin single pane rear cog. which is lighter than 10-13 speed rear cassette. The setup of the Driven bike will be fifteen to twenty percent lighter than a traditional drive-train. The traditional drive-train setup is also bound by the thickness of the cassette, as number of gears can be included int he cassette depends on the width and thickness of the chain. The Driven bike is not limited by the thickness of the cassette, so you can expand the cassette to have up to twenty speed cassette. The only limiting factor is the movement of the pinion that slides to shift gears.
The shifting of gears occurs when the pinion slides forward and back, selecting one of the gear rings. Ceramicspeed envisions that the shifting will occur using wireless electronics inside the pinion, which will have a battery, motor, and linear motion actuator. The setup will be completely electronic and contained within the shaft with very compact and clean design. When you shift, it can’t shift instantaneously and randomly because they have taken out a lot of teeth. Instead, there are five shift channels that are linear and parabolic with a magnetic sensor. Depending on the rotational speed of the rear cog, the radio position of the rear cog and pinion shaft, the electronics will know which shift channel to use when you are riding along and a shift command is initiated. To the rider, the shifting will seem relatively instantaneous as it will occur in a fraction of second after initiating the command.
The shaft has an eight bearing pinion in the front and eleven bearing pinion in the rear, which provides gear increase and by changing the pinion diameter, you can change the overall gear reduction or increase of the drive-train so you don’t have to change the cog or the front ring. Ceramicspeed envisions a modular design that will allow the rider to change the drive shaft by switching to different pinions. This means that within a minute, you can change the overall gear ratio of your drive train, so you can have a hill race on one day and next day you can have faster race course. All of this happens while looking very futuristic with clean and slick design without the rear derailleur.
Advantages of the Driven Bicycle:
- Driven is lighter than a conventional drivetrain as the chain and derailleurs are eliminated
- There is a high potential for aerodynamic advantages
- Lower friction in general, and the elimination of chain link stiction and chain sliding friction
- Endless possibilities for gear range options of a 1x gear.
- Different diameter front and rear pinions can be used to increase or decrease the overall final drive ratios.
- The prototype contains a 13-speed rear cog, yet additional gears could be easily added
The Driven bicycle concept has won the Eurobike 2018 Award after evaluation and assessment of 366 entries by independent panel of experts judges. We are still skeptical of the functionality and durability of this design under real world conditions.
Source: Ceramicspeed
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