Market and supply base grows for e-bikes

  • 10-Sep-2010 10:47 EDT

The components of the Bosch e-Bike System for bicycle electrical propulsion assist are (from left to right) the battery pack, the HMI (human machine interface) display and control, and the electrical drive with motor, control unit, and sensors.

The growth in the market for e-bikes—bicycles having electric-propulsion-motor assists—was on full display at the Eurobike bicycle trade show in Friedrichshafen, Germany, held in early September. Electric drive options from traditional suppliers are now being challenged by systems being designed by interlopers from the automotive industry.

One notable example from a traditional supplier was by Fallbrook Technologies Inc. The company showed a next generation of its NuVinci drivetrain that is over 30% lighter and 17% smaller with enhanced shifting. The N360 CVP (continuously variable planetary) transmission transmits mechanical power with spheres instead of gears.

With an unlimited number of ratios available within its nominal 360% ratio range, the NuVinci CVP is an attractive replacement for bicycle derailleurs and internally geared hubs because it can provide a better ride and shifting experience.

Compared to the NuVinci bicycle drivetrain launched in 2007, the N360 provides a significantly reduced shift effort even under high pedal forces, and there is 50% less twist rotation required to move between the lowest and highest ratios, the company claims. For better protection, the hub interface is now housed inboard of the frame drop-out.

The new transmission was developed in response to bicycle manufacturers' calls for a smaller and lighter drivetrain so they could put it on more models. It will be offered on many additional bicycle models including the Gepida Reptila, Mosquito Classic Energy, Raleigh Dover 360, and Victoria NuVinci.

"The N360's ease of shifting is particularly beneficial for e-bikes," said Alan Nordin, Fallbrook's Bicycle Division President. "E-bike riders will shift more, and that can result in less battery drain when starting up or going up a hill, which in turn equates to increased battery range."

For bike dealers and owners looking to upgrade existing bicycles, an N360 aftermarket conversion kit is available.

The Eurobike show also witnessed a major automotive supplier entering the electric-bike space. Bosch unveiled an electrical-drive assist system it calls e-Bike, pre-production examples of which were fitted to numerous bicycles at the event. Various bike OEMs are testing the Bosch system, which is expected to begin delivery on production bikes in spring 2011.

The company's strategy is to transfer its relevant automotive technology development experience to other applications or industries, in this case electric bicycles, to take advantage of social trends such as energy saving, e-mobility, and health consciousness.

Bosch is investing in different fields relating to these long-term trends. Company officials believe that e-bike drives are an important part for sustainable mobility concepts for the future.

The e-Bike system is said to offer a bicycling "feeling" despite the electrical assist. It also offers more design freedom for bicycle manufacturers. This was reflected in the variety of models—mountain, trekking, or touring bikes—on display at the trade show. Controls supplier Magura will join U.S.-based bikemaker Cannondale as a Bosch service partner for the new system.

The Bosch system features three modular components. The drive unit, battery pack including charger, and handlebar HMI (human-machine interface) control unit are said to present a lighter weight alternative to competing systems. Another claimed benefit is greater drive safety due to a lower vehicle c.g. that it provides.

The compact 288-W·h lithium-ion battery pack, which Bosch claims can be fully charged in 2.5 h or 50% charged in 1 h, is available in different build configurations for frame or carrier fitting.

Built with three sensors that measure speed, torque, and pedaling cadence, the system is said to deploy requested drive power efficiently and unobtrusively. Drive characteristics are programmable, allowing four distinct setups (Eco, Tour, Sport, and Speed) for different types of bicycles.

For instance, the drive could deliver its power more dynamically for a sporty mountain bike than a touring bike meant for greater range. If a bike maker enables more than one of the four levels, a rider will be able to select the appropriate level of control for a given road or riding situation, according to Bosch.

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