We take a closer look at the CeramicSpeed DrivEn concept and ask ‘will it work?’
We are very passionate about design and our small team all cycle. We ride mountain bikes, downhill bikes and of course road bikes so of course, we have been discussing the DrivEn concept here in the office. We sat down with Tom (owner of Aetha Design) to see what he thinks about this concept and how it could change the cycling industry.
As a cyclist and product designer, I find it incredibly exciting to see this level of innovation in a sport that typically sees marginal, iterative improvements between product releases when it comes to drivetrain technology. The basic concept of using a chain to drive a gear has been around since Leonardo Da Vinci drew a chain drive in the 16th century. Mountain bike company Pinion is leading the way with internal gearbox options as a replacement for the standard derailleur, but these are yet to hit the mainstream consumer.
CeramicSpeed started working on the DrivEn project 18 months ago with the aim to create a drivetrain with 1% frictional losses or in other words, 99% efficient. They enlisted a team of engineers from the University of Colorado Engineering Department to help develop the concept.
How does it work?
The DrivEn concept uses ceramic ball bearings to engage teeth on a flat cassette to convert a pedal stroke by the cyclist to drive the rear wheel. The bearings roll through the teeth and therefore, create zero sliding friction. The system gets its efficiency gain from replacing the 8 points of sliding friction in a standard derailleur system, with 2 points of rolling friction. They say the system is around 49% more efficient than a standard derailleur system.
Weight gains have been achieved in the process of removing components such as the chain and derailleurs but are replaced by batteries and shafts, they say this could be 15-20% lighter than a standard setup but it’s early days.
To change the overall gear ratio (usually done by replacing the front chainring with a different number of teeth) they envisage a quick release method of replacing the entire carbon fibre axle (electronics and all) with a different ratio between the front and rear bearing pinions. The current design has 8 bearings at the front and 11 at the back to create a mechanical advantage.
Because the cassette is flat and doesn’t rely on a chain moving up and down the gears, in theory, the cassette could have any number of gears (up to the diameter of the wheel!).
So how would it shift?
This is the question I asked myself as soon as I saw the concept online. Yes, it can drive a wheel on a single gear ratio but I couldn’t find any video of it changing gear. There is a cut-away section of inside the carbon fibre tube which contains a battery, wireless electronics, motor and linear actuator.
The principle of the bearing pinion sliding fore and aft up and down the gears works in principle but in reality, this is extremely difficult to achieve without stripping the gear’s teeth. They say it uses ‘shift channels’ where the bearing pinion is able to jump between gears at several points in the rotation. This would be interesting to see how it wears when changing gear under torque. For this to work, the system will need to index itself and know where the ‘shift channels’ are in relation to the bearings.
The big question is…will it work?
Once they have got it shifting between gears, the next consideration, in my opinion, will be reliability. How soon with the gears wear? Will the bearings slip across teeth as they wear and the obvious consideration for any designer is real-world testing….so outside the lab, with the introduction of dirt, grit and grime from the average ride, what happens? And then the age-old Di2 argument, what happens when you run out of battery on a ride?
Only time will tell if this goes from a very exciting new concept to an actual reliable consumer product, but one thing we do know is there’s a long way to go. All I know is we would love to see this level of innovation being made into a reality in an industry with marginal evolutionary changes so we hope they get there!
Images courtesy of BikeRadar and CyclingTips.Read more News