The following article appeared in the August 2000 edition of Bike europe. The Rabbit Tool hub motor offers the possibility of regenerative braking at very high efficiencies by way of feeding the current back to the batteries during descents or speed reductions.
Equipped with regenerative braking for extended range

Rabbit Tool Introduces AC Hub Motor for E-Bikes and Pedelecs
by Hannes Neupert

Rock Island, IL/USA - At just 16 kilograms, the new Rabbit Tool EX Bike from the USa sets new standards for electric bikes. Yet as attractive as its aluminum frame (from Dahon) and minimum weight design might be, Rabbit Tool has pieced together its e-bike to showcase something a lot closer to its heart: motor technology. The EX Bike is fitted with a high-technology AC hub motor for e-bikes, pedelecs and other light electric vehicle applications. Boasting of high flexibility in design and performance, it is the first hub motor on the market that combines braking with regenerative power.
Not to be overshadowed are the 7 or 13 Ah nickel metal hydride batteries continued in close-fitting aluminum tubes in order to optimally disperse the heat generated during charging. The standard charge takes two hours, and the charger is designed to sense the state of the batteries. This type of so-called smart charging greatly extends battery life. The charger comes in a metal case the size and shape of a cola bottle, so it can be easily transported. A one-hour charger is currently under development. It goes without saying that the batteries can also be recharged on solar power.
Rabbit Tool has developed the Dahon bike as a showcase for its motor technology. At just 16 kilograms, the EX-Bike sets a new standard for e-bikes.
OJ Birkestrand heads this mechanical engineering firm making small machine tools in Illinois, USA, and has been developing the electric wheel’s hub motor assembly for several years. Motor, throttle, controller and battery pack are designed to be fitted to existing vehicles with minimum modification. Birkestrand is keen to emphasize that Rabbit Tool is not a developer of vehicles: the Dahon machine is a technology demonstrator, designed to show manufacturers of existing lightweight vehicles the potential of their new motor and battery technologies.
AC motor hub
Rabbit Tool’s new motor is a gear-reduced brushless AC design with a continuous rating of 300W and comes in a number of versions, ranging from standard front and rear wheel to an ultra-compact design which, fitted with an 8-inch wheel, is also suitable for wheelchairs, lawn mowers, handcarts, etc. Particularly interesting is the model with one-side wheel support and an integrated disk brake, ideal for multi-track recumbents, transport bikes or trailers. Rabbit Tool’s motors are up to 95% efficient in a wide range of conditions, and different windings are available to suit the required torque. The motor also offers the possibility of electric and even regenerative braking braking at very high efficiencies by way of feeding the current back to the batteries during descents or speed reductions. Rabbit Tool’s patented technology opens up exciting new possibilities for e-bike and pedelec manufacturers. The regenerative braking is powerful enough to make normal braking a rarity (used only, say, in emergency situations), and it has the potential to greatly extend the range of electric vehicles. Moreover, the batteries can be recharged simply by lifting the rear wheel off the ground and pedaling. They can even be used to generate stationary power - ideal for camping.