there is a concept similar to the optibike already
(using the gears of the bike)
this are the Biketec Flyers
the F-series, the T-Series, the S-series, ...
the bikes are very well known in swizzerland, Italy, Germany and Austria...
to be one of the most quality bikes around
all available with different configruations (fomr 3speed, 5speed-hub, 7speed-hub, up to 14speed rolof-hub)
and different frame sizes
its also very inovative..
(for example: unlike all other (cheap) pedelecs, it does not measure the revolutions of the biker and than kicks in: it measures the torque with a torque-sensor..
so when starting from a stand-still it helps from the very first cm you drive and not like most other bikes who need 1-3meters until they kick in (which is bad when you stand on a hill with a trailer, lot of weight and want to start driving))
prices range from 1500Euro up to 6000euro i think for the top models..
its also more quiet than the opti-bike because the motor is directly driving the pedals, no gears/planetary inside the motor --> nevertheless it uses all the gears of the bike itself (which can be up to 27)
another very good bike with a very unique (patented) and good drivetrain ist the http://www.swizzbee.ch/
on this bike you have the invinite possibility to how much you want to assist or not..
its too complicated for me and my poor english to tell you how it works.. (also i donÃƒâ€šÂ´t get it by 100% for myself)
but it has something to do witht he sun and planetary-gears...
you spin the planetary-gears, the motor the sun, and the sum of it powers the bike..
so you can deside how fast you pedal without regearing...
difficult to explane for me
very unique and nice to drive..
it seems that it is also available with fuel cell:
120km of distance with that
see this picture: http://www.swizzbee.de/images/press/focus_27092004.jpg
price is also high...
4000euro the bike...
+ the batteries (or 1000Euro the fuel cell)
nevertheless: the opti-bike has the nicest frame..
downside: you canÃƒâ€šÂ´t change the batteries fast..
when i go to work i would want to take the battery with me into bureau to charge it..