In article eda70eef-beae-4d33-8318-c502c1c60e72
@m34g2000hsf.googlegroups.com, TerryJ
says...
On 21 Jan, 20:29, Mark T
pleasegivegenerously@warmail*turn_up_the_heat_to_ reply*.com.invalid
wrote:
Bottle dynamos - all they do is suck power and make a funny noise. Today I
saw a reverse bottle dynamo; one that ADDS power. The working mechanism
sits stealthily over the front wheel - might be good for the peeps worried
about their TT times

www.flickr.com/photos/86862441@N00

I asked about this kind of thing recently and it was suggested that
this is not legal in UK. Where did you see it?

It's perfectly legal to use in the UK if you register, tax and insure
it, have a valid license and wear a helmet. I suppose you could also
use it as a bicycle if you made the engine inoperable.