with good power and great handling because of weight-balance
so.. i like this idea here (maybe even more than a hub-motor):
the wheels keep light, and you can use the gears on your rear-wheel, so
--> high speeds when going onroad
--> low speeds when going up steep hills
here some very good pics:
i would like to use an Outrunner
on the pics i could see that the gearing with the chain is about 1:4,5 ?!?
would you agree ?
so the paddels need to go with about 80-90U/min
with 1:4,5 ---> so the motor-output should spin 400rpm/min
when i look for Rc-plane-Motors:
for example this Orbit 30-14:
peaks of 2500Watt are possible (just to show what the motor is cabable)
and it weights only 305g
(but even if it was 600g it would be unimportant when you think that you and your bike are over 100000g
this motor would spin - i prefer higher volts over higher amps because of better efficience -
at 27Volt with about 12000rpm - 13000rpm
(i have used Outrunners with only 7000rpm in my heli.. and its running way not that powerfull and efficient like a outrunner with double rpm and higher gear-reduction)
so: to get the 400rpm we would need a 30:1 Gear-Reduktion
hmm - that should be possible to be achieved by a two-stage belt-drive
so: 7:1 first stage with smaller belt and 4:1 at second stage bit bigger, stronger belt
that should be relative quiet as well, i bet ?
to protect everything you can laminate a case from Carbon (would also look cool)
and seal everything as well (to protect from dirt)
when you drive a bike with full suspension, the electric driveline-parts would beguarded by the suspension, wheels would be still as light as normally for good performance and handling offroad
for the batts:
i would not take LIpos..
Lipos are too fraquile, and - when treated wrong way - can burn..
i would go with A123-Systems FePO4 cells, the new technologie..
benefits of the cells:
can handle up to 50C currents
can be charged with 4C (= 15min charging time)
or - if you except a lifetime of the cells of "only" 200-300 cycles - even with 10C (full to 95% within 5min !!!)
the cells have a hard-case like NiMh,
the are absolut safe (will not burn unlike LIpos)
and have a shelf-lifetime of 10 years (lipos only 2-4years)
and a cycle-life in such a bike-application of FAR over 1000cycles (more like 2000-3000cycles)
compared to NiMh (100-200cycles in reality) or Lead-acid (500cycles)
a HUGE benefit !!
you can get that cells cheap when buying DeWalt 36Volt-battery-packs from ebay..
(they are used in power-tools)
3 packs would cost 300Euro
and delivere 36Volt (under load about 27volt) and about 7000mAh
the cells have the same high voltage from start until end of discharge, so unlike NiMh, LiPos or lead-acid, you will not notice any power-loose until its there...
and: a 7000mAh-Pack can easily handle 200A continously and 300A peak..
(that would mean: 10cells, 2,5Volt, 300A --> 7500Watt Peaks *lol* - not needed, just shows that you can not stress this cells to death in a bike like you can with lead-acid !)
weight of such a 36V-7000mAh-Pack: about 2200g