The Ellsworth Ride with NuVinci CVP Hub
by Warren McLaren, Sydney 
on 03.28.07
Don’t be fooled by the elliptical frame, the built-in fender (mudguard) tailight, the chainless belt drive or the carbon fibre components. Oh, no. What is more intriguing here is the NuVinci CVP hub drive. NuVinci because it is a modern industrial adaptation of an idea that the inventor of the parachute and tank, Leonardo da Vinci himself apparently conceived, some 500 years ago. CVP because it stands for Constant Variable Planetary transmission. Not that tells you much more. (It means it has no fixed gear ratios.) But let’s try this instead: “The NuVinci transmission uses a set of rotating balls between the input and output components of a transmission that tilt and vary the output speed of the transmission. Tilting the balls changes their contact diameters with the discs, which varies speed.” Still none the wiser? Watch the little demo video and all shall be revealed. At the moment all there is to see are some computer renderings. We trust they will materialise into real products. Fallbrook Technologies, who make the drive, say it can be scaled up to work on electric vehicles, agricultural equipment and wind turbines. Ellsworth who make the bikes, beginning at $3,000 USD, say they are first to put the NuVinci into a bicycle. Which they reckon is high on speed and stability whilst low on maintenance. ::Ellsworth Ride, via a tip from Lloyd, who first espied it at Core 77.
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This is very interesting! I'm just thinking of how much more efficient wind turbines could be with this.
Looks nice, but I'm still worried about how much traction the spheres will have.
Only $3000 US? I'll take 3!
Andrew,
A CVT inout to output is less efficient than a chain drive, so there is friction losses and slippage. (Overall as a system with an engine they are more efficient since they keep the motor at a more optimum RPM and efficiency which more than makes up for this inefficiency)
Since 27 speed (9 speed rear cassette) is so common, there is rarely a point where a rider does not have an appropriate efficient gear, but I imagine the sales of this will be to people who hate fiddling with adjustments on cables and derailers.
wow, it has low maintence costs, who cares when the bike is 12 times the cost of a comparable bike, but i would like to have it in my car, it would make changing gears much more easy
I've done research on CVT's(Continuously Variable Transmissions (of which the CVP is one kind) and friction is always the problem. No one has ever been able to conceive of a geared CVT, they all rely on friction.
However, car manufacturers have been able to start using CVT's lately (Audi, Mini, Nissan, etc) and they have been used on snowmobiles for years. So I suspect that if they can work for cars they can work for bikes. Although they will probably always be more expensive and less efficient than a chain and gears.
Conventional bicycle hub gears tend to be less efficient than derailleur gears, but not much.
When you look at the Nuvinci demo on their website, you will see that there aren't that many parts involved in this special "hub", compared to a friction-prone conventional bike internal hub gear (with two or three planetary gear units placed serially to achieve the desired wide gear-ratios).
As I understand it, the Nuvinci hub uses a special fluid which produces a mechanical gear-like transmission of power when under heavy pressure and acts as a lubricant the rest of the time.
(I think CVT-belt drives could use this miraculous fluid too to prevent slippage.)
So I think it might be able to keep up with a derailleur gear efficiency-wise.
Yeah, its awsome and everything, but also THREE THOUSAND DOLLARS! Seriously, I'd wait a few years for the price to go down.
This bike is $3000, but you can buy just the hubs for $400.