• The Copenhagen Wheel

    The Copenhagen Wheel

    Photo courtesy of the SENSEable City Lab

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  • A close-up of the Copenhagen Wheel, from MIT's SENSEable City Lab.

    A close-up of the Copenhagen Wheel, from MIT's SENSEable City Lab.

    Photo courtesy of the SENSEable City Lab

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  • The Copenhagen Wheel in action

    The Copenhagen Wheel in action

    Photo courtesy of the SENSEable City Lab

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MIT’s big wheel in Copenhagen

The Copenhagen Wheel

New bicycle wheel not only boosts power, but also can keep track of friends, fitness, smog and traffic

It looks like an ordinary bicycle wheel with an oversized center. But packed inside that unassuming hub is a veritable Swiss army knife’s worth of electronic gadgets and novel functions.

The new wheel, developed by researchers at MIT, can store energy every time the rider puts on the brakes, and then give that power back to provide a boost when going uphill or to add a burst of speed in traffic. But there are also a variety of extra functions hidden within the hub of this new wheel, which is designed to be easily interchangeable with any standard bicycle’s rear wheel.

By using a series of sensors and a Bluetooth connection to the user’s iPhone, which can be mounted on the handlebars, the wheel can monitor the bicycle’s speed, direction and distance traveled, as well as picking up data on pollution in the air, and even the proximity of the rider’s friends. The resulting data can both help the individual rider — for example, by providing feedback on fitness goals — and help the city (if the user opts to share the information) by building up a database of air quality, popular biking routes or areas of traffic congestion.

All of the generating, power assisting, sensing and communications equipment fits inside a plastic housing in the hub of the wheel, connected to the standard rim by a novel system of spokes. Dubbed the Copenhagen Wheel, it was developed by Carlo Ratti, associate professor of the practice in MIT’s Department of Urban Studies and Planning (DUSP) and director of the SENSEable City Laboratory, and his team.

The whole generating and power-assisting system can be controlled through the pedals, requiring no switches or dials. Pedal backwards, and the regenerative braking is engaged, helping to recharge the system’s batteries; pedal fast, and you get the extra boost of power. “Everything is controlled by your feet,” Ratti explains.

In addition, “The wheel, thanks to the energy it harvests, becomes something that helps you keep track of your fitness,” he says, by recording the mileage that you travel. That information could also be shared, for example, with employers, who might get credits for the avoided pollution for employees who commute by bike. It also contains sensors that can monitor levels of carbon monoxide, nitrous oxides, temperature, humidity and noise, and a GPS that can track position.

There are a variety of bicycles on the market now that can provide an electrical boost, but Ratti says his team’s is different because of its extra functions, modern design and ease of use. The city of Copenhagen, site of the UN Conference on Climate Change, has been a sponsor of the research (along with the Italian company Ducati, and the Italian environment ministry), and the city has already placed an initial order for some of the innovative bicycle wheels, to be used by city workers.

The system was demonstrated in Copenhagen on Dec. 15 for the benefit of conference attendees, and for a gathering of 400 city mayors from around the world.

‘Biking 2.0’

Assaf Biderman, associate director of the SENSEable City Lab, says that Copenhagen makes a perfect testbed for the system because of its heavy bicycle usage. “It’s a city with 500,000 people and 600,000 bicycles,” he says. “This device can change your experience of riding, and change your experience of the city.” Moreover, data about the daily routes bicyclists use could help city planners determine where more bike paths are needed, and fine-grained data on pollution might help officials pinpoint its sources.

“Over the past few years we have seen a kind of ‘biking renaissance,’ which started in Copenhagen and is now transforming the urban experience in many cities from Paris to Barcelona or Montreal,” says Ratti. “We could also call it a ‘Biking 2.0’ revolution, whereby cheap electronics allow us to augment bikes and convert them into a more flexible, on-demand system.“

Ritt Bjerregaard, the Lord Mayor of Copenhagen, says the wheel may well help her city achieve its goal of getting half of its citizens to bike to work or school every day. “For us, this project is part of the answer to how can we make using a bike even more attractive,“ she says.

But some experts are more circumspect. Rob Sadowsky, executive director of the Active Transportation Alliance, a Chicago-based organization that promotes increased use of bicycles in urban areas, says that some elements of the Copenhagen Wheel — the ability to track and post on social networks, for instance — differentiate it from other add-on devices already on the market. However, he questions whether electric bikes and related technologies can boost the number of cyclists on the roads.

“While electric bikes have a role to play, in communities such as Chicago, I'd say that it would very minimal,” he says.

Christine Outram, a research fellow in DUSP who has been working on the project, explains that the two-way link to a user’s iPhone, which can be mounted to the handlebars, can also be used to control some functions, as well as to display information.

The extra functions could provide a wealth of data to help the city analyze a number of environmental factors. Outram says that at present, the whole city of Copenhagen has just three sensors monitoring pollution, all mounted on tops of buildings. If the new bicycle wheel becomes widely adopted, there could be thousands of sensors all over the city at street level. “Now, through a small amount of technology, we could have an incredible amount of information,” she says.

Ratti says the team expects to have the wheel in production by the end of next year. The retail price has not yet been determined. Though the prototypes cost hundreds of thousands of dollars each because of all the research involved, their analysis shows that a regular production model can be “competitive with existing electric bicycles,” he says.

“We’re showing that biking can really help some of today’s problems in cities — congestion, pollution, climate change,” says Ratti. For the bicycle user, there’s another advantage to the embedded electronics: security. Because of its built-in Bluetooth connection to the user’s cellphone, the wheel can be set so that the bicycle will only function if the user’s cellphone is within range. “The bicycle will recognize the presence of the phone and unlock,” Ratti explains. “When you leave, it locks,” without requiring any specific action by the user.

Topics: Copenhagen, Energy, Environment


Maybe if I have said, we do it with words, the invention will come, as in "reinventing the wheel". I think this is truly a fascinating bicycle wheel, with so many functions. It's interesting to me, that we humans, endlessly not only invent, but seem to need so many gadgets and find a need for them. You would think this bipedal human being once we got "wheels" would have been pedaling along in this way forever. But then we got so much more, airplanes and other flying machines, and now this add to our old wheels.

Maybe we will find cures to all the "wheals" of life.

Copenhagen is a bold, brave effort to cope and I look forward to what comes out of these meetings.

Where can we buy one of these? Do they need user testing? Please say the store, and please say yes.

it's a amazing. Well, you can't imagine that many people taking a tour with it, it's a wonderful idea

I think this a very innovative idea. Especially in densely populated areas like India and China this would be a boon. And would cut down emission rates by folds. But since the cost of the product was not mentioned will it be viable it all????

The Good: Data collection for optimization of needed bike lanes.

The Bad: No data on increased weight burden vs. realistic "boost" effectiveness.

The Ugly: I need an iPhone to unlock my bike?

Considering the price point, you would basically be tracking traffic data of rich people (... our data seems to indicate that most of the bike traffic is on weekdays around 10am. It seems to be flowing over to this coffee shop that serves $9 lattes... guess we had better put in a few more bike lanes around there...)

Congratulations to Ratti, who has given form to something that I only dreamt about!

When I was a graduate student in Course 2, I co-invented an energy storing bicycle wheel. (Patent 4744577.) Purely mechanical, it was designed to store energy from braking, and release it for re-accelerating. We never made a product of it, and in fact its only purpose was to reduce energy losses when a route had many stop-signs.

In the last few years I have become convinced that an electric wheel would be a very significant development in fostering bicycle commuting. First of all it would easily add power assist and regeneration to any personally preferred bicycle in just one minute. Secondly, as long as it could start the day with a fully charged battery, it could be set to multiply the pedaller's power by a factor of 2 or 3, turning any ordinary rider into a Lance Armstrong, flattening hills and making any ride faster.

Such a product confers two benefits:

The first has to do with commuting. In the modern world, office workers are extraordinarily sensitive to bicycling problems -- time, inability to carry loads or passengers, the likelihood of getting sweaty. The result is that the current 'MEDIAN TOLERABLE COMMUTE DISTANCE' is probably down around 2.5 miles (while the median distance from home to work could be 10 miles). Power assist can potentially double this ‘tolerable distance’, which could quadruple the number of people who find themselves within commuting distance of work.

The second relates to fitness. An ordinary powered vehicle provides no incentive for the user to perform any exercise. However a 'power multiplier' requires pedaling input, and rewards increased effort with a marked increase in speed.

Ratti has actualized what I imagined, and also added many additional electronic features that I never even considered. In our cheap-energy society where so many live so far from work, if bicycling is ever to play a larger role in daily life, it requires developments such as this to give bicyclists a far-extended practical range.

Jim Papadopoulos '79, Ph.D. '86, co-author of BICYCLING SCIENCE 3rd Edition (MIT Press).

Why on the back wheel? I want to replace my front wheel not my backwheel!!! Why no solar panels? iPhone?!?! geez... But most importantly why only a prototype... build and distribute it already! Let's get the wheel rolling on this one...

The Segway uses a bluetooth "key" to lock/unlock, power on, and display status. Clearly the wheel can have it's own dedicated key, or an App on any Bluetooth enabled device - iPhone or Android or etc...

Nice idea. Love the distributed data collection - and let's add accelerometers for mapping road condition!

What is holding up mass production and sales of the Green Wheel? I've been following this product for almost a year and a half and it doesn't seem to be going anywhere in terms of availability. Is this something that's never to be realized and it's only that someone hasn't said so? I have a daily 27-mile roundtrip to pedal in frequent, strong windy conditions. It's a major deterrent to make the choice to ride it without some sort of assistance. ...didn't want the fossil fuel option, but the other electric options aren't perfected well enough to justify the cost of short-lived & expensive batteries filling up the landfill. Where is the Green Wheel?

Batteries are already there for a 27 mile round trip and if you charge mid way you don't need half as much capacity. This device whilst it looks very nice, it's not going to give a very meaningful assist for a long ride. There is only so much energy it can store from an external charger and the amount of regeneration it can use is only going to give you occasional boost.

I can say with almost 100% certainty this high tech device will be significantly more expensive than a small geared hub motor setup and small li ion based pack.

This is not a downer on this device, far from it, I'm just stating that IMO electric bikes are already there as a viable form of transport with available and relatively inexpensive parts. Large EVs are still some way off as a completely viable replace for an ICE vehicle for every situation IMO. You don't need bluetooth and environmental sensors to get you to the office without breaking into a sweat :)

I am a handicap that rides a 3 wheeled bike (Hand-cycle) powered by my arms only (no leg power). This unit would be a great help on rides like the the one I take twice a year in San Francisco over the Golden Gate and up the coast of Monterey. There's a lot of hills that are a challenge to say the least. It would be neat to adapt it to the front wheel or maybe even consider one on each back wheel. Could they be synchronized? When will they be available?

HHMMMMM. This would make my life much easier.

Hey you! I am very interesting with the Disareinmo Bike, some people say that is very used and very better that The Copenhagen Wheel. Is it true? We want to know your knowlege about this. Louis Henry, Dakota

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