Brian Malone
Industrial
- Jun 15, 2018
- 399
Ceramicspeed has continued development of their Driven drive system for bicycle propulsion. Original thread:
Update links:
Their engineering team has been very creative and busy developing amazing technology to address the issue of making the Driven system shift: 'step and follow' drive pinions with a torque-decouple bearing synchronizer. Though they show a shifting demonstrator model and CAD animations, I don't think a shifting system has actually been ridden and shifted by a world-class racer to show it can deliver power reliably and efficiently at high input levels.
Their demonstrator still appears to be an interesting concept that promises a lot but still requires a lot of work:
1. The rear cog set has cogs inward to the hub OD but the driving pinions cannot reach those cogs due to the geometry requirements of the step and follow driveshaft, and the material required to make the frame dropouts to attach the wheel axle. So the extreme range of ratios shown does not represent the true working range.
2. The inherent side force created by the driving bearing in the driven cog will try to deflect the drive cog cluster and driver cog apart. The stiffness of the drive to maintain engagement will be challenging, especially at the outer/lower ratios.
The demonstrations appear to be orchestrated to some level. Ceramicspeed does not show the system in use at the smallest radii. They stay within what appears to be a known good range. The track test never zooms in in on the setup used by the rider. I think he is riding a fixed ratio setup - track riders do not shift gears. I don't think they have allowed independent testing to confirm their claims for mechanical efficiency - but that is not uncommon for many products in development. I get it - to keep the R&D dollars flowing you have to emphasize the successes and soft-shoe the remaining technical challenges.
It will be interesting to see if this is a viable tech or a 'better mousetrap' that is different but not really better. A chain and two sprocket set are rugged, efficient, low-cost, and reliable.
Update links:
Their engineering team has been very creative and busy developing amazing technology to address the issue of making the Driven system shift: 'step and follow' drive pinions with a torque-decouple bearing synchronizer. Though they show a shifting demonstrator model and CAD animations, I don't think a shifting system has actually been ridden and shifted by a world-class racer to show it can deliver power reliably and efficiently at high input levels.
Their demonstrator still appears to be an interesting concept that promises a lot but still requires a lot of work:
1. The rear cog set has cogs inward to the hub OD but the driving pinions cannot reach those cogs due to the geometry requirements of the step and follow driveshaft, and the material required to make the frame dropouts to attach the wheel axle. So the extreme range of ratios shown does not represent the true working range.
2. The inherent side force created by the driving bearing in the driven cog will try to deflect the drive cog cluster and driver cog apart. The stiffness of the drive to maintain engagement will be challenging, especially at the outer/lower ratios.
The demonstrations appear to be orchestrated to some level. Ceramicspeed does not show the system in use at the smallest radii. They stay within what appears to be a known good range. The track test never zooms in in on the setup used by the rider. I think he is riding a fixed ratio setup - track riders do not shift gears. I don't think they have allowed independent testing to confirm their claims for mechanical efficiency - but that is not uncommon for many products in development. I get it - to keep the R&D dollars flowing you have to emphasize the successes and soft-shoe the remaining technical challenges.
It will be interesting to see if this is a viable tech or a 'better mousetrap' that is different but not really better. A chain and two sprocket set are rugged, efficient, low-cost, and reliable.
