Electric bicycles, with some exceptions, generally fall into one of two categories: those that can be powered solely by their motor, and those in which the motor is only used to augment the rider's pedaling power (commonly known as "pedelecs," or pedal-electrics). In both cases, they can also simply be pedaled, without any contribution from the motor. California electric vehicle designer Roy Prince, however, decided that he wanted all three - a bike that could be motor-driven, pedal-assisted, or just plain pedaled. The result is his intriguing creation, the eCortina v2 hybrid.
Prince's bike started life as a standard off-the-rack Cortina Triton DS hardtail downhill mountain bike, and was transformed within a three-month period early this year. Among other things, it now features a motor and controllers originally designed for use in radio-controlled models. Those motors are powered by two packs of lithium-polymer batteries, which are electronically monitored while the motor is in use, to extent their lifespan by avoiding over-charging and over-depletion. Running in parallel, the battery packs have a combined output of 48V-10Ah.
The dual drive system mostly uses standard bicycle parts, including two BMX-style freewheels - these are what allow the eCortina to be pedaled without motor assistance, or to be motor-driven without the pedals being engaged. Beefy BMX chains are used throughout, while a 3-speed Shimano Nexus rear hub is also incorporated.
Although Roy is still working out the performance and range parameters, he estimates that the bicycle should be able to travel about 15 miles (24 km) on one charge, given mild riding demands and some pedaling. With the addition of two more battery packs, he hopes to boost that distance to 23 miles (37 km). Using the motor alone, it is geared for an invigorating top speed of 45 mph (72 kph).
Tipping the scales at just under 60 pounds (27 kg), however, it's certainly no lightweight. Considering Prince's design intention, however, that's OK - "Realistically the eCortina must be considered a motor bike with human assist," he states on his website.
Source: Bicycle Design