Note lack of cars in centre of city....
CityCyclingEdinburgh Forum » Cycling News
"MIT re-invents the wheel, for bicycles"
(7 posts)-
Posted 16 years ago #
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This must be a wind up wheel then.
Says there are no additional batteries?*
* Ah.. you mean that the batteries rotate in hub? Sounds like an evil plan.
PS - Interesting to note that the biggest buyers of electric bikes are in flat countries!
Posted 16 years ago # -
"wind up"...
All a bit odd. Even if it were super-efficient there's not too much energy to be saved when you brake. So does it detect when you are freewheeling and become a dynamo (slowing you down)?
How big a battery/capacitor can you get in the hub with a motor?
Posted 16 years ago # -
I did some calculations a year or so ago i had a similar idea...
Travelling at 15 mph or 6.7 m/s and weighing 100kg inc bike you'd have about 630 Joules of energy. Braking over a 5 second period you would generate about 120w, not bad but you would need a really clever dynamo to recover any thing like that and still be an efficient drive motor.
Posted 16 years ago # -
Ooops embarrassingly for my first post i've picked up the wrong numbers.
http://en.wikipedia.org/wiki/Kinetic_energy
Ek= 1/2(mv2)
Ek= 0.5*100*(6.7*6.7) = 2248 joulesPosted 16 years ago # -
More info, inc. designer's web site
Posted 16 years ago # -
Now there is an idea for the Edinburgh Vélib scheme should it ever happen. OK so they might need to change the smart phone bit, but then again that could be use as a way of hiring the bike. It has electrical assistance to get the rider up the hills, it has built in security, and it even collects environmental data in real time for the council. What is not to like?
Well the council would rather not have the NOx data, as that would mean they would actually have to do something about it, rather than just ignoring the issue as they do now.
Posted 16 years ago #
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