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Saturday, May 2, 2009

GreenWheel Electric Wheel

TECHNOLOGY - Imagine having an electric-powered bicycle... but without the big clunky battery attached to your bike frame.

The next time you change a bicycle wheel, think about upgrading to a wheel that comes with its own motor/generator and a built-in battery. Created by scientists at MIT the new GreenWheel can turn any regular pedal bicycle into an electric bicycle. The bike can still be pedaled like a regular bike, but is now a electric-hybrid bicycle.

"Just take the wheel off, put a GreenWheel equipped wheel on in its place, plug it in and it should work just fine," says 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."

The GreenWheel has the radius of a small dinner plate and is about 2 inches thick. Inside the GreenWheel has an electric motor/generator, batteries and is surprisingly lightweight considering its purpose and usefulness.

Installing GreenWheel on your own can be rather difficult so its recommended you get a bicycle mechanic to do it for you. The GreenWheel requires an higher level of technical knowledge, but can be installed on any bike frame or wheel size. The original spokes have to be replaced with shorter spokes. Learning how to re-spoke a wheel and then true a wheel is rather difficult and not for amateurs. See Wheel Truing.

A bike powered solely by a single GreenWheel (front, rear or both wheels can be equipped with a GreenWheel) has an estimated range of 25 miles on a full charge. Pedaling occasionally doubles the bike's range under electric power, allowing the generator to store more energy whenever you pedal, brake or slow down. The bike can also be charged by plugging it into the electric grid.

The ride is just as smooth as normal and the noise from the electric motor is barely a hum even when at you turn the throttle up and down. The handle-mounted throttle is connected wirelessly using BlueTooth technology to the electric motor in the wheel.

The GreenWheel is also durable and the MIT team estimates its range is 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," says Lin. (Unless you know a good bicycle mechanic, of course.)

The GreenWheel team is currently planning to pass out more than a dozen different GreenWheel configurations to both hard-core cyclists and novice riders in order to get feedback on how well it works before promoting. Using that feedback the MIT team will determine the optimal configuration of power, speed and cost before starting large scale production.

Copenhagen and South Africa have already expressed interest in adding GreenWheel-equipped bikes to their public transportation systems, creating a bike share program similar to a program in Paris France which is 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. City planners and GreenWheel designers hope to reduce the use of fossil fuels and carbon emissions by getting more commuters out of their cars and onto bicycles.

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 bicycles, but they typically have heavier and more environmentally destructive lead based batteries (however lead based batteries almost never need to be replaced unless they are in a crash). Designer Chin expects a privately purchased GreenWheel will cost between $200 to $400.

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 known as SmartCities. SmartCities hopes to expand the range and ease of public and private transportation. They are also designing an electric scooter and a stackable electric car.

Rod Sadowski 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 every transportation problem.

"The biggest barrier to people getting out of cars and riding is that they don't feel safe," says Sadowski, who explains that cities need more bicycle trails, paths and lanes. "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."


  1. I want two for my bike. I will be watching this very closely. I will buy them as soon as possible.
    The price is right.

  2. I would buy one of these if they need test subjects. I have a 20" rear wheel KMX Typhoon Trike. I'm right across the river from MIT so I could be available for beta test feedback, and modifications. Please forward this to the MIT folks. Thanks

  3. But, Where's the Wheel? I have not seen where these can be purchased.



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Charles Moffat is equal parts bicycle mechanic, cyclist, painter, sculptor, fantasy writer, poet, website designer and pun maker. For more details see



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