Bicycles

"World’s most efficient" bicycle drivetrain unveiled at Eurobike

"World’s most efficient" bicyc...
The CeramicSpeed DrivEn system would have to be built into new bikes – it couldn't be retrofitted to existing models
The CeramicSpeed DrivEn system would have to be built into new bikes – it couldn't be retrofitted to existing models
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The CeramicSpeed DrivEn system would have to be built into new bikes – it couldn't be retrofitted to existing models
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The CeramicSpeed DrivEn system would have to be built into new bikes – it couldn't be retrofitted to existing models
The CeramicSpeed DrivEn system incorporates a total of 21 ceramic bearings 
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The CeramicSpeed DrivEn system incorporates a total of 21 ceramic bearings 
The CeramicSpeed DrivEn system's chainring
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The CeramicSpeed DrivEn system's chainring
The CeramicSpeed DrivEn system is claimed to be 99-percent efficient at transferring pedalling power
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The CeramicSpeed DrivEn system is claimed to be 99-percent efficient at transferring pedalling power
The CeramicSpeed DrivEn system was developed in partnership with the Mechanical Engineering Department at the University of Colorado, and has just received the 2018 Eurobike Award
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The CeramicSpeed DrivEn system was developed in partnership with the Mechanical Engineering Department at the University of Colorado, and has just received the 2018 Eurobike Award

Of all the items currently on display at this year's Eurobike show in Germany, one of the most attention-getting is CeramicSpeed's DrivEn pinion-style shaft-drive system. According to its designers, it creates 49 percent less friction than the high-end Shimano Dura Ace chain-and-derailleur setup.

At the heart of the prototype drivetrain is a cylindrical carbon fiber shaft, that reaches from the single chainring in front to a flat 13-speed cassette on the rear wheel.

Mounted on either end of that shaft are sets of very-low-friction ceramic bearings (there are a total of 21 of them), which engage the teeth on the chainring and the cassette cogs. As the rider pedals, the bearings transfer torque from the chainring through the shaft and into the rear wheel, turning it.

In its current form, DrivEn can't shift between gears, although BikeRadar reports that this could conceivably be managed using a wireless servo to move the rear bearing mechanism fore and aft relative to the cassette.

The CeramicSpeed DrivEn system incorporates a total of 21 ceramic bearings 
The CeramicSpeed DrivEn system incorporates a total of 21 ceramic bearings 

"CeramicSpeed has proudly accomplished what many have said couldn't be done," says company CTO Jason Smith. "We achieved a 99-percent efficient multi-speed drivetrain while eliminating the chain and complex rear derailleur."

That efficiency is reportedly achieved due to the fact that the system does away with the eight points of sliding friction that are present in a regular drivetrain, where the chain articulates while passing through the chainring, cassette and derailleur.

DrivEn was developed in partnership with the Mechanical Engineering Department at the University of Colorado, and has just received the 2018 Eurobike Award. There's currently no word on commercialization.

And for another take on the shaft-drive bicycle idea, check out the Alpha Bike concept.

Source: CeramicSpeed via VeloNews

20 comments
f8lee
So for the moment it's a fixie - kind of nifty looking but without the ability to change gears anyway somewhat pointless...
axio
Hmm... looks nice, but: - aah.. how does it change gears? that's far harder said than done.. - is it comparing efficiency to the default Dura-Ace chain system out of the box? Because the default chain oil used is sticky like honey and is renowned for its friction... everyone cleans that right off and uses a lighter oil.
T N Args
@f8lee, it clearly isn't *meant* to be a fixie. You are just seeing Stage 1 before they complete the project with a 13-speed mechanism. Extremely not-pointless. In fact, it is the end of the derailleur for those who aspire to the best.
Johannes
Even if they can solve the gear change problem with a sliding pinion, that flimsy gear-set will flex so much that the pinion rollers will jump teeth on the bigger cogs. It's a "no" from me.
duncan06
it does not change gear and it is a tiny amount more efficient that the system that does Guess what if I modify a derailleur system so that it does not change gear then I lose that inefficiency as well!! - so the gear/chain system will be just as efficient as this monstrosity
owlbeyou
Never thought of the derailleur system as inefficient. It certainly doesn't hold anyone back from the enjoyment/workout it gives. Was hoping for a video demonstration. The cassette diameter will be prone to flexing, as Johannes says, can't change gears yet, and what is the weight difference between the two methods? Is this meant for competition cycling? Would the average cyclist have incentive to buy it, and at what cost?
Towerman
I like it a lot, but it will have to be made very strong.
Lardo
Here's the problem with gear changing; In order for the "pinion" to move back & forth through the "cassette", each of those rings will need to be separate parts. And will somehow need to synchronize with each other. Even if that is possible, you’ve now added a good amount of complexity. And, therefore, cost. T N Args is mistaken. The derailleur isn’t going anywhere, anytime soon.
Douglas Bennett Rogers
All it needs is a freewheel at one of the three rotation points and a spring loaded sleeve on the shaft.
Paul Anthony
This is remarkable