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.

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.

Hybrid......

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!

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.

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?

"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.

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..

@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?

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 peak...so, 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?

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.

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.