Principal Investigator Kent Larson
Project Website http://cp.media.mit.edu/greenwheel/
The GreenWheel is a modular, electric-assist wheel that can easily be fitted to any standard bicycle. It was first prototyped and demonstrated by Smart Cities in September/October 2008.
The GreenWheel’s design packages the essential mechanical and electrical elements in a compact, modular hub unit that (1) complies with the demanding form constraints of a standard bicycle wheel and can be fitted to any standard bicycle, (2) requires no wires or other physical connections to other parts of the bicycle, and (3) provides an attractive combination of high performance, high reliability, and low manufacturing cost. The modular design of the GreenWheel also allows it to be customized for different contexts and uses without changing its overall form.
The GreenWheel does not alter the look and feel of a bicycle or the familiar experience of riding a bike. It discreetly provides some assistance when and where you need it – for example, when facing a challenging hill, when the weather is particularly hot, when you want to commute to work without getting sweaty, or when you simply want to keep up with younger and fitter riders. You just set your desired level of pedaling effort, and the GreenWheel automatically kicks in when you exceed that. It also cuts out when you stop pedaling.
GreenWheel bikes are classified and regulated as bicycles. You can ride them anywhere you can ride a manual bicycle, and you don’t need a scooter or motorcycle license.
The GreenWheel uses the latest high-performance lithium-ion battery technology. The batteries can be recharged in just 1-hour from a standard 110V electrical outlet or faster, if desired, from special charging racks. They are long lasting, reliable, and provide sufficient capacity for a full day’s riding.
The GreenWheel is highly energy efficient, inexpensive to operate, and minimizes the carbon footprint of your daily personal mobility. When recharged at night, and operated under normal urban conditions, it consumes less than a dollar’s worth of electricity per day.
The GreenWheel can certainly be used as an effective element of new bicycle designs. Its more important benefit, however, is to enable convenient retrofit of the world’s vast existing fleet of conventional bicycles. Electric assist, provided in this way, can open up the practical possibility of bicycling to a much larger part of the population. It can make bicycling more feasible in hilly cities, and cities with hot climates, where bicycle use is currently constrained. And it provides a low cost, low risk pathway to the large-scale introduction of clean, silent, efficient electric vehicles.
The advantages of this path to electrified personal mobility are profound. An electric automobile weighs twenty times as much as its driver – with motor, battery, energy supply, and charging infrastructure requirements to match – and generally costs at least $40,000, but a GreenWheel-equipped bicycle weighs much less than its rider and can cost less than $1,000.