Ellsworth/NuVinci's CVT concept bike

Ellsworth's CVT

So the biggest promise of the whole show may come from the Ellsworth/NuVinci concept bike.

Its NuVinci drive system is the latest shot at what many engineers have called “the Holy Grail” for inventors, a continuously variable transmission. The idea of a CVT is that instead of having distinct gears, a mechanism somehow provides a way for an input and output to change their relationship smoothly to “gear up” and “gear down” smoothly, without jumping from gear to gear.

Here's the page on CVTs from Howstuffworks: It notes that the first CVT patent was granted in 1886, and that US carbuyers have been able to buy CVT autos since 1989, but that most automotive systems use a pulley system, where a belt moves higher or lower in a gap between two cones, changing the effective size of the pully.

The NuVinci system, on the other hand, borrows from planetary drives, enough that its manufacturers call the NuVinci a “CVP” system, or Continuously Variable Planetary. In this design, a series of 3-12 drives function as the “planet” gears in a planetary system with a movable cage altering their relationship to the “sun” gear. The whole thing is bathed in a new fluid from Valvoline called Inveritorc.

Cars generally control their CVTs through onboard control computers, figuring what ratio is best for given engine horsepower and torque. The NuVinci leaves that to the rider, so you will have an adjustable input, probably like a motorcycle throttle, that lets you choose “harder” or “easier” in any interval at any time. Suddenly hit the bottom of a big hill? Twist that grip all the way down. Want to pedal 3 more rpm on the flats? Twist it a little.

Of course, only time will tell whether this mechanism's going to stand up to everday (ab)use.

The Ellsworth is deserving of mention even if it were sporting a Sturmey-Archer 3 speed hub: It's a gorgeous combination of cruiser-bike and motorcycle styling cues, slathered in immaculate Ferrari red, and even includes partial fenders.

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