Electric Bicycles.

[Dynamic Position]

I was trying to find "The Don Bike" and came across: Wapedia - Wiki: Motorized bicycle.
From the first Giant Lafree design patent to Cytronex. Its amazing to think that e-bikes are rooted so deep in history.

 

[Barnowl]

I love the steam powered bicycle. That must have been an interesting ride.

 

[flecc]

They certainly are. I used to sell, fit and service the petrol add-on bike motors in the 1950s which started the main trend, here's an example of the sort of thing, though the first add-on petrol cyclemotor was in 1912, the Wall Autowheel which was an add-on side wheel and motor. It wasn't until the start of the 1990s that the electric assist bike really hit the commercial market, though they had hardly any penetration until about year 2000. This delay was hardly surprising considering how weak the early ones were and how crudely designed. One used a truck wiper motor for example, and many used friction drive onto the tyre tread.
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[Dynamic Position]

I will have to try and get a photograph of the Don Bike. It is one of the petrol versions flecc mentioned but it is one of the best designs I have seen. The steam bike looks interesting and would be very practical if you could boil some water for a cup of tea on a day trip.

 

[the_killjoy]

Wouldn't that steam thing ride better with engine at the back ?

How about something more conventional :

http://www.scienceandsociety.co.uk/Pix/TRN/%2034/10221434_T.JPG

My favourite in the science museum is an old coal burner bike that was alledgly found in a ditch after failing to finish the first london to Brighton.