>-----Original Message-----
>From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] 
>Sent: 05 May 2006 17:47
>To: 'Microcontroller discussion list - Public.'
>Subject: RE: [ee] Basic physics... Bicycle regenerative braking forces
>
>
>> Dragging this back on topic I personally think mechanical
>> systems have too many problems to be practical.  How do you 
>> smoothly control the transfer of energy from kinetic to 
>> potential?  It implies some kind of friction clutch is 
>> required, and also some kind of mechanism to make sure the 
>> potential energy isn't released too quickly.  Complexity and 
>> weight, both natural enemies of the humble bicycle.
>
>Using the brakes on the front wheel only and the mass of the 
>rider and bike behind it to compress a spring (hinged frame 
>with coil spring, flexing frame with leaf spring, telescoping 
>frame with air spring) and then the standard Sprague clutch on 
>the rear wheel to prevent the release of that energy until the 
>front brakes are released. No additional components, easy to 
>control via the front brake.

James,

What I meant was how would you control the transfer of energy into the spring?  A simple clutch gives you either none or full regenerative braking.  Idealy you would have some kind of variable ratio drive so you could actualy control how quickly you slow down.  If the system is permanently geared then in many situations it will either be too little and you have to fall back on normal friction brakes, or too much.  And of course you would need to include a mechansim to prevent too much energy being input, i.e. disconnect regenerative brakes once the spring is wound up to maximum.

I know when you have a hammer everything looks like a nail, but I reckon this application would only be practical using electrical storage.  Springs, compressed gas, flywheels etc. are all too bulky/heavy/dangerous.  The above problems are all overcome by a relatively simple electronic control system.

Regards

Mike

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