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Friday, March 11, 2011

Pi Electric Bicycle with Semi-Automatic 8-Speed Transmission

The Pi electric bicycle uses a semi-automatic 8-speed transmission to downshift into a lower gear for climbing hills, then up shift for rapid acceleration to a maximum of 20 mph on flats and allows you to pedal normally because the motor automatically disengages when not in use. Powered by a 750-watt electric motor housed in the horizontal chain and motor assembly, the Pi electric bicycle is capable of three modes of operation: electric motor power, human power, or the human-electric hybrid power combination. The electric motor and rider utilize the same 8 speed semi-automatic transmission making rapid acceleration from a stop or lower gears available for steep inclines possible (but with slower acceleration.The motor automatically disengages from the pedals when desired so as to preserve battery life. Construction begins with a 12’ foot straight piece of 3⁄8-gauge, aircraft aluminum 6061 alloy that is roll-formed and annealed for uniform wall thickness into a complete 6′ diameter circular tube with a 4″ exterior diameter (the NiMH batteries reside within the tube from the front fork to the seat), which is then bisected to make a 6′ long arc for the bicycle’s frame. The sturdy frame supports riders up to 300 lbs.

The top of the arc provides a 26″ stand over height, allowing you to place both feet on the ground. The padded ergonomic gel seat provides for comfortable, relaxed riding. It attaches to the frame via a gas strut assembly that raises and lowers like a pneumatic office chair, accommodating riders between 5-7′ tall in a semi-recumbent position for ideal pedaling or powered coasting. A dynamo in the front wheel’s hub provides power for auxiliary lighting.

The bicycle has a range of up to 30 miles at 20 mph before requiring a five-hour re-charge from its AC adapter. Precisely tuned hydraulic disc brakes provide sure stops, and the wheels are made of dual-walled aluminum alloy and stainless-steel spokes; the 26″ semi-slick tires are ideal for roads or paved trails and use Presta valves. The bicycle is wet-painted in Rossa Corsa red using the same PPG color specification as high performance sports cars and treated with a clear coat finish for a luster that will last.


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