By Jim Langley
Jim’s Tech Talk
By the time you read this I’ll be on vacation and enjoying some beautiful riding along the seacoast of New Hampshire and Maine. If you spot me on my blue Bike Friday Pocket Rocket Pro give me a wave!
I was in a rush to pack my gear and skedaddle, so this Tech Talk is a quickie, but hopefully interesting nonetheless. I want to show and get your comments on the fascinating new drivetrain from CeramicSpeed that debuted at Eurobike, which just took place in Germany. I couldn’t attend but caught the highlights on the GCN channel here:
CeramicSpeed is calling their amazing new drivetrain Driven and claiming that it’s the world’s most efficient drivetrain (at 99%), topping chain and derailleur drivetrains which have been the most efficient seemingly forever.
Here’s a nice video discussing the Driven’s innovations courtesy of bike guru Shane Miller (aka GPLama).
As you would expect, Driven caught everyone’s attention. Yet lost in the fanfare is that something like this happened over 100 years ago in the late 1890s. Back then, though, chains and sprockets were nowhere near as refined and efficient as today’s. Some were hardly smooth at all.
So there was way more incentive to improve things and inventors came up with what became known as the “chainless” bike. Like CeramicSpeed’s Driven, these antique drivetrains utilized a shaft to transfer the power from the crank to the rear wheel. But instead of bearings, they used different types of meshing gears.
Several world records were set on chainless bicycles, some by arguably America’s greatest-ever, Major Taylor, who rode an Orient Chainless made in Waltham, Massachusetts to many victories the world over.
Yet, as successful as they were at the races, the meshing gears on the shaft, chainring and rear hub were heavy, wore quickly and made it difficult to remove the rear wheel. Then, chains and sprockets improved significantly and – while chainless bikes like those old ones still exist, they are not at all mainstream.
It’ll be interesting to see if the Driven drivetrain can make the grade and revolutionize our future bicycles. But, even with its modern bearings and materials plus infinite gearing options it’s only a tiny bit more efficient than chains. And it seems like adding shaft-drive mechanisms to frames in production could be a challenging hurdle. I wish them luck.
Please see CeramicSpeed’s Driven webpage to learn more.
Ride total: 8,968
How long will the exposed bearings last in a real life outdoor riding situation? It seems like to me that once they get dirty or worn from dirt that any advantage there may have been for watts used is lost.
John Tonetti says
Seems like a solution in search of a problem to me… I don’t think my drivetrain is my greatest source of cycling inefficiency, and the marginal gain is… well… marginal.
Brian Nystrom says
The main problems with it are:
1 – The bearings are open, which means they’re quickly get contaminated with dirt and the 1% increase in efficiency will go out the window. If you put seals on the bearings, the 1% increase in efficiency will go out the window.
2 – The flat driven disk will flex under any significant torque, which means that most of the “gears” toward the outside will skip as it flexes under pressure.
3 – The tiny fingers on the drive and driven disks will bend and break easily.
4 – They haven’t figured out how to shift it and it may not even be possible to do so.
This is an interesting engineering exercise with probably no practical applications in the real world, with the possible exception of track bikes and other single speeds. At least it’s a pretty neat example of out-of-the-box thinking…
Nicholas Gimbrone says
The shifting is addressed in this video: https://www.youtube.com/watch?v=-9gQ1KRhesM
Eric Irwin says
I think that this is somewhat interesting, but they must have hit a real hurdle in developing the shifting mechanism since it doesn’t exist yet. I can’t imagine showing a totally new technology like this at a show without it being 98% functional. It is also very worrisome that there is a tremendous amount of backlash in the system. There are points in both of those videos where you can see that the bearings do not mesh very precisely with the gears. That is something that anyone who has ever designed or worked with geared systems knows will lead to a lot of wear.
What is left out of both of these videos is that the whole thing was developed at a CO university. That is not necessarily a bad thing, but it probably explains the somewhat incomplete nature of the prototype. Schools work around timelines based on semesters. The projects get as far as they can in the given timeframe. I doubt this would be shown if Ceramic Speed was developing this in-house.
Bike Fitness Coaching says
I will just stick with my Penny Farthing (https://en.wikipedia.org/wiki/Penny-farthing) which has a 100% efficient drivetrain!
Brian Nystrom says
That’s a very astute observation! I guess you could say the same thing about a tricycle, too…
Richard Atkinson says
Wait till the UCI get their hands on it. I am sure they will find some excuse to ban it. I mean if a pro rider falls off and lands on that rear sprocket it could do untold damage. 😉 😉