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GreenWheel Turns Pedal Bike Into Electric Hog




Feb. 18, 2009 — The next time you change a bike tire, think about upgrading your power as well. Scientists at MIT are testing a new power generation, storage and propulsion system known as the GreenWheel that will turn any pedal bicycle into an electric hog.

“Just take the wheel off, put a GreenWheel equipped wheel on in its place, plug it in and it should work just fine,” said Ryan Chin, one of the GreenWheel designers. “The whole thing has been designed so all the parts except the throttle are enclosed in the wheel.”

From the outside, the GreenWheel has the radius of a small dinner plate and is about 2 inches thick. Inside the aluminum frame sits the three major GreenWheel components: an electric generator, batteries and an electric motor.

For now, installing GreenWheel on your own does require a moderate level of technical knowledge or a trip to a bike shop. The GreenWheel can be installed on any bike frame or wheel size, but the original spokes have to be replaced with shorter spokes. Michael Chia-Liang Lin, a master’s student at MIT developing the GreenWheel, called his parents in Taiwan, who own a bike shop, to figure out how to respoke the wheel.

Under its current configuration, a bike powered solely by a single GreenWheel (front, rear or both wheel can be equipped with a GreenWheel) has an estimated range of 25 miles. Pedaling the bike doubles the range under electric power, provided the rider isn’t traveling at the nearly top speed of 30 miles an hour. The bike can be charged by pedaling or by plugging it into the electric grid.

A GreenWheel equipped bike is a smooth ride, as Discovery News found out during a recent afternoon test ride around MIT’s campus. Turning the handle mounted throttle, like any motorcycle, just a few small degrees produces a noticeable increase in power and a light electric hum. The handle-mounted throttle is connected wirelessly to the electric motor in the wheel.

The GreenWheel is also durable. The team estimates its range at 40,000 miles, or about eight years work of travel at an estimated 20 miles per business day.

“You’ll have to replace the bike before you replace the batteries,” Lin told Discovery News.

By this spring the GreenWheel team hopes to pass out more than a dozen different GreenWheel configurations to both hard-core bike messenger types and novice riders.

Once the optimal configuration of power, speed and cost is determined the team hopes to begin large scale production.

Copenhagen and South Africa, in preparation for the 2010 World Cup, have already expressed interest in adding GreenWheel-equipped bikes to their public transportation systems. The rough idea right now is to follow a popular bike share program in Paris. Subsidized by advertising revenue and an annual subscription, the first 30 minutes are free, and any time after that incurs a small fee.

The Paris program has been widely viewed as a success, one which Copenhagen hopes to build on. By getting people out of cars and onto bikes or public transportation, city planers and GreenWheel designers hope to reduce the use of fossil fuels and carbon emissions.

Besides cutting carbon emissions, the GreenWheel is also made from environmentally friendly processes by companies like A123 Systems, which manufactures the lithium ion batteries used in the GreenWheel.

Other systems exist to convert pedal bikes to electric scooters, but they typically have heavier and more environmentally destructive lead based batteries. While an exact cost hasn’t been nailed down yet, Chin expects a privately purchased GreenWheel to cost several hundred dollars.

Other electric bike converters cost up to $1,200 and require running wires to and from motor to battery to handlebar throttle. Since batteries, generator and motor are all one part connected to the throttle by Bluetooth technology, installation is also easier than existing conversion kits.

The GreenWheel is an offshoot of another MIT project the team members are part of, known as SmartCities. SmartCities hopes to expand the range and ease of public and private transportation. The GreenWheel is the latest addition to SmartCities line of vehicles, which also includes an electric scooter and a stackable electric car.

Rod Sadoswki of the Active Transportation Alliance thinks the GreenWheel could encourage some individuals to ditch the car and take up commuter biking, but doesn’t think that technological fixes are the answer to transportation problems.

“The biggest barrier to people getting out of cars and riding is that they don’t feel safe,” said Sadowski. “As a society we need to place a stronger focus on creating laws to stop incidents from occurring and on upgrading infrastructure to make every road bike-friendly.”