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MIT Bringing Smart Biking Project to Copenhagen; Prototype Hybrid Bicycle

Exploded image of rear wheel of prototype hybrid smart bicycle. Battery, motor and electronics are all packed in the rear wheel. Click to enlarge. Credit: MIT

MIT researchers at its SENSEable City Laboratory have unveiled a project in Copenhagen aimed at transforming bicycle use, promoting urban sustainability and building new connections between the city’s cyclists. The project, called SmartBiking, will utilize a novel self-organizing smart-tag system that will allow the city’s residents to exchange basic information and share their relative positioning with each other.

As part of the project, a prototype of a smart bicycle is being developed in collaboration with the MIT Media Lab’s Smart Cities Group. This hybrid bicycle harvests the energy created when braking and releases it while cycling. All hybrid-drive elements, including the battery, are packed in the rear wheel, which becomes a self-contained component that could be retrofitted on most existing bicycles.

A considerable fraction of [Copenhagen’s] energy comes from renewable sources and, unlike a few decades ago, 30 to 40 percent of its citizens use bicycles as their primary method of transportation. So our challenge was, ‘How can we enhance these dynamics of sustainability? And how can we use technology to make them more widespread?’

—Carlo Ratti, Director of MIT’s SENSEable City Lab, which is overseeing the Smart Biking project

The smart tags will allow individuals to monitor the distance they travel while cycling as part of a citywide “green mileage” initiative, which is similar to a frequent-flyer program. Ultimately, fine-grained monitoring of urban activities could allow cities such as Copenhagen to enter carbon-trading schemes. Cities could obtain funding for sustainable city services in exchange for their efforts to cut carbon dioxide emissions. The impact could be considerable, as cities account for approximately half of the world population, but are responsible for a much larger share of carbon emissions.

Beyond encouraging Copenhagen’s citizens to ride more often, the program aims to help them interact as well. A Facebook application called “I crossed your path” creates a social network for cyclists, allowing them to link up with people they may have ridden past during the day and potentially establish new connections, according to Christine Outram, the principal research assistant on the project.

The project will be implemented citywide in time for the November 2009 UN Climate Change Conference, which Copenhagen will host.

The Smart Biking Project is developed by the SENSEable City Laboratory, an MIT research group focused on technology and urban planning that is a part of the MIT Department of Urban Studies and Planning, together with the MIT Design Lab. In addition to professors Ratti and Mitchell, the team comprises Assaf Biderman, Francesco Calabrese, Michael Lin, Mauro Martino and Outram.

Concept of the MIT Wheel Robot. Click to enlarge.

Among the MIT Smart Cities Group’s projects is the CityCar, a stackable electric two-passenger city vehicle. The CityCar utilizes fully integrated in-wheel electric motors, energy storage integrated in the axle, and suspension systems called “Wheel Robots.” This technology is patented-pending and under design development at the MIT Media Lab.



This project can have much more impact to free from oil addiction than all this complex cellulosic ethanol, PEHV etc.


You wonder if it is worth it - surely existing P-bikes are enough for most purposes.

On the other hand, an e-bike with a LiOn battery could be good, especially if you put recharge stations all over the place - coin operated - if you could recharge your bike for 10c (euro) it would be a bit of a no brainer.

Then, you would need 1/2 the battery capacity compared to having to charge at home.

The great thing about e-bikes is that their energy requirements are so low that it doesn't matter where the power comes from - it can come from coal fired power stations and it won't matter - if you get home in 250wH.

It might be the case that marketing these bikes as hybrid electric will make them sexy enough to get people on to them - and that would be a result in itself - getting people onto bikes is primarily a marketing problem, not an engineering one, and if the magic H word is enough to make the difference, so be it.


We can find in UK the cardboard bicycle !


Kevin Cameron

I'm a big fan of gearless in-hub motors but I don't understand why they want to put the battery in the hub.

It creates a lot of problems:
Exposing the battery to motor heat
Battery cooling is more difficult
On vehicles with suspensions, the battery will be exposed to large accelerations from road bumps
Battery size is limited to what will fit inside the hub
The battery form factor is fixed and limits the possibilities for modifications or dealer options

Against those drawbacks, I don't see any advantage. It seems unlikely that in-hub batteries will become popular in EVs of any size.


I don't get the batteries in the hub either.

Rabbittool had worked on this concept long ago. They did regenerative braking, which I'm assuming MIT does as well, but they don't state explicitly.



cool to call "half human power / half electric" a "hybrid-bike".

It's true of course, and really smart to jump that band wagon. The smart thing of "in hub" batteries is of course that retrofitting becomes a no-brainer. It is also smart to reduce low voltage-high amp cable-length, and to pack all electronics in a waterproof compartment.

If these batteries (I count 16) are A123 26650 cells then you would have a 13,2 V / 9.2 Ah battery pack (4S4P), capable of helping the bike at 120 Watt, during 1 hour. That is a serious amount of "push" and could make a daily 16 kilometer (10 mile) commute a lot easier. The battery would weigh just 1 kilo / 2 pounds.

Doing all this math : I'm going to find out where I can get one!


@Kevin Cameron, Jim,

There are advantages in putting the battery in the hub. It is cheaper to manufacture, the resulting wheel can be mounted on a standard bicycle frame. You can easily take the wheel out to repair/change a tyre without disconnecting cables. No corroding contacts, loose connectors, broken cables. Bicycles are not treated like cars. They are thrown around and have to be robust and simple. In case of a bicycle it's definitely better than a separate battery.


There are pro's and cons the the hub battery.
The main con being that you might not want an extra Kg or 2 in the wheel + you get the most vibration there, and if you have soft tyres to reduce this, you lose efficiency.

You will have to have contacts to charge it, so you don't lose them, you just put them nearer the road spray.
The 16 A123 cells alone weigh 1.12 KG - this is just the cells, not the complete power pack.
+ they are good for 1000 cycles = 2 years @ 250 x 2 charges - which is not so good.
You might have to use more cells and limit the duty cycle to 50% (sigh).

But the idea of a minimalist e-bike is interesting - IF you can recharge it at you destination ad get the battery life figured out.

Will it have regenerative braking ? - if so, it will probably need a supercap or you will lose a lot of power in hard braking.

An urban system could use regen. braking, a suburban one wouldn't, but could use more energy for longer runs.



The main con being that you might not want an extra Kg or 2 in the wheel

Bikes for city use usually do not have suspension, and if they do, it is mostly the front wheel only. So putting the weight in the rear wheel does not matter.

You will have to have contacts to charge it

I thought it was a HEB, not a PHEB.

Will it have regenerative braking ?

The article says so:

This hybrid bicycle harvests the energy created when braking

Healthty breeze

I don't think regenerative braking as the sole charging method is nearly as exciting as PHEV bike.

People would want the boost when accelerating, going uphill, on long straight aways, or when facing a head wind.

120 watts is about .16 BHP. A strong cyclist produces about .25 BHP. This is a serious push. If you think about cycling, the acceleration is much more tiring than steady speed. Making acceleration easier, and being able to "take a rest" while cruising along at 30 Kph would dramatically increase the stamina range of the cyclist.

I think people would appreciate that push so much that they would be willing to replace a $200 battery every couple years. How much would an A123 battery pack cost for such a bike?


A HEV bicycle is a crazy idea - all it can do is store braking energy, and for this you add a motor, a battery and all the associated control gear.

Much better to double or triple the battery size and add a charging connection.

E-bikes could be really good if they can get the mix of cost, speed, range, looks and weight right.
- Easy! - just a marketing problem (ahem).

No-one seems to have done it - most look awful, except Schwinn, but they are very expensive ~$2k.

Their power requirements are so low, they could revolutionise urban transport with almost no CO2 or fuel use impact.

Lets hope some company cracks it - we need a Steve Jobs of e-bikes.


"The smart tags will allow individuals to monitor the distance they travel while cycling as part of a citywide “green mileage” initiative, which is similar to a frequent-flyer program."

They'll also allow the government to track the block-by-block location of my bike. Great if it's stolen and we're trying to track it down, terrible if it's me on the saddle.

Please don't use "green" as an excuse to track movement of people -- either on bikes in Denmark or in cars in Oregon.


RFIDs - they are a part of the future that needs serious regulation.

Henry Gibson

Reliable connectors are easy to make. A couple of ZEBRA cells in a Dewar (Thermos) flask would make a replaceable battery pack to charge what every other batteries might be used.

In Denmark the greatest majority of the power is produced with CO2 release; the percentage of renewable wind generation is low. Much hydro power is brought in from Norway on cables.

Electric bicycles are old and even lead acid batteries are suitable for their operation especially in Denmark.

Because of the large amounts of development efforts going into LiIon batteries they will work, but the price will remain high. A lead acid special battery pack from EFFPOWER would be useful and buidable tomorrow and perhaps Firefly can learn to make foam good enough for it. ..HG..



Sparta is pretty close with their design. They put the battery in an oversized down tube:

MSRP starts at € 1800 including taxes, but I have seen them in stores for under 1300.


@Henry Gibson

About buying hydro power from Norway: don't the Danes export a lot of power to Norway? Aren't they using Norwegian hydro for regulating the fluctuations of their wind power?

Interesting facts

Henry Gibson,

Even though average living standard is the same or even higher in Denmark than in the US:

Denmark: 10.94 t of CO2/capita (U.S. DOE (2005))
USA: 20.05 t of CO2/capita (U.S. DOE (2005))

Healthy Breeze

How much supercapacitor capacity would this little system need to maximize efficiency and battery life?

I'm thinking 8-10 seconds of hard acceleration or deceleration is about the most it would need to accomodate at, to me that suggests having a small supercap which could handle 16-20 seconds of peak discharge or charge, and programming the system to try to keep it at 8-10 seconds (50% capacity) as it's ideal set point. That way, you've always got enough juice for one good push, and enough capacity to accept the energy from one hard braking. When it is full, you use energy from the capacitor first to drain it down to 50%, and then use batteries. When it is at zero, you pull any available charge from the batteries to raise it up to 50%.

This should reduce the stress on the battery, thus extending its life. This should accept more of the energy from hard deceleration, thus extending range and efficiency.

Somebody who knows, please advise how big does a supercap have to be to hold the energy captured when a 100 KG vehicle (including rider) decelerates from 30 KPH to 0.
Would it currently be practical to have double that
volume in the hub of a bicycle wheel?
What would that cost?


Somebody who knows, please advise how big does a supercap have to be to hold the energy captured when a 100 KG vehicle (including rider) decelerates from 30 KPH to 0.
At 12 Volts you need almost a 50 Farad capacitor.


What has this "smart" communicating big brother bike to do with green policy? Is it a good thing that others know your bike's position? This is not smart, it is just another 'big brother is watching you' idea if you ask me.

It is fashionable to confuse 'smart' stupid ideas with eco friendliness.


Agreed - bicycles are one of the last unregistered forms of transport - there is no need AT ALL to track where we go electronically.
I am sure they can do it from cameras, but that would be a bit of work - using RFIDs would be trivial to track, and it would be abused.

Nonetheless, bikes and e-bikes are excellent forms of urban transport in moderate weather - in terms of fuel economy, road space usage, environment and personal health (p-bikes) - and they should be encouraged.

Even if LiOn batteries are expensive, you should need so few that the cost will be reasonable. 3-400 Watt hours should be enough for most people.

You could consider adding them to a rucksack so they are not left on the bike, and if you chose to cycle without power assist, you do not have extra weight + they could be used as laptop power extenders.


This is a cool idea and it will be interesting to see if it takes off. In my neighborhood there are lots more e-bikes around these days.

One big inhibition to mass adoption of biking in the West at least, is the inequitable favor given to motor vehicles. And the extremely lax application of traffic law. Car-centric cultures breed car-centric drivers who believe the roads belong to them and people on flimsy bicycles are intruders.

Pedestrian and cyclist accidents have increased dramatically in the last ten years following the increase in cyclists. This ends up costing vehicle owners more as the accident rate increases insurance premiums. If bikes and walking are to be realistic contributors to energy conservation - a serious overhaul of traffic enforcement and moving vehicle violations must take place.

Expect such overhauls to be resisted by stubborn drivers, car clubs, and law enforcement itself.


good point
it's not just traffic enforcement and vehicle violations that need to be overhauled, it's the entire infrastructure that must be overhauled

anyone who has visited, traveled or lived in Holland must have noticed that they have been working on the entire transportation infrastructure for many decades, maybe close to an entire century. They have not only laws, but trams, trains, buses, protected lanes for bicycles and sidewalks everywhere for pedestrians, not just cars

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