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Throttle and pedal for a cocktail of e-bike fun

March 1, 2012
Even the traffic capital of the world Los Angeles hasn't been able to resist the fun of electric bicycles (e-bikes) — and maybe you won't, either.

Even the traffic capital of the world, Los Angeles, hasn't been able to resist the fun of electric bicycles — and maybe you won't, either. At the forefront are pedalec bikes that allow mixing and matching of input as needed. Cyclists simply pedal like on a normal bike, while getting a proportional boost from an electric motor when desired. More motor assist can be supplied when tackling longer distances or particularly nasty hills, for example.

Marketed by Currie Technologies, an Accell Group company, Chatsworth, Calif., one bike called the IZIP Express integrates what's billed as the Evo-Drive. As Larry Pizzi, president of Currie Technologies explains, “Through various phases of development, this hybrid drive has been referred to by many names — Dolphin, Syntelli — but ultimately, we settled on Evo-Drive.”

This integrated drive is a dual planetary system housed inside the bike's rear-wheel hub. It combines human power input on the right side of the wheel (through a conventional 27-speed bicycle drivetrain) with the power from a 750-W dc electric motor (on the opposite side of the hub) through a fiber-reinforced pulley — driven by a notched belt from Gates Corp., Denver.

The human-powered drivetrain consists of a classy SRAM Rear Derailleur, PowerGlide 950 11-32T 9-speed Rear Cassette, Shimano Front Derailleur M580-E, and a Shimano triple chain-ring crankset. The electric motor is a brushless (permanent-magnet) four-inch frame motor, proportionally regulated by motor controls. As is common in pedalecs, electric power is only actuated when one pedals. Additional sensors cut motor power completely when the rider stops pedaling or hits the brakes.

Where does the motor get its power? A high-capacity lithium-ion battery pack powers the motor, and sits inside the bike's main triangle-shaped frame.

As Pizzi points out, 40% of all urban trips in the U.S. are less than two miles in distance, but 90% of them are made by car — a trend he hopes to change.

Besides the Express and other models, the IZIP E3 Metro also exists. This bike is lighter than electric bikes of yore and capable of two modes: In what's called “twist-and-go” (TAG) mode, the throttle triggers 100% motor power, which is added to any pedaling. In “pedal-assist-system” (PAS) mode, on the other hand, the motor is triggered to output half of its full power when sensors detect that the rider has started pedaling.

To find a local dealer, visit currietech.com, or drop by the official IZIP Store in Venice, Calif.

About the Author

Elisabeth Eitel

Elisabeth Eitel was a Senior Editor at Machine Design magazine until 2014. She has a B.S. in Mechanical Engineering from Fenn College at Cleveland State University.

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