I have heard a lot about electric motorcycles using a driveshaft, but have only ever heard of one person who ever actually did one.
Reverend Gadget's shaft-drive electric cycle.
In terms of gearing, electric motors have lots of torque, but if you spin a motor slow and gear it for speed, you pull much higher amps, which will shorten the life of your brushes and batteries, and limit range.
It is much preferable to spin a motor faster and gear it down. This uses less amerage and extends range. This trait is also one reason why electric vehicles have typically been designed as slower-speed, reliable vehicles, such as golf carts and personal mobility vehicles.
A higher voltage system also limits amperage draw because you need to use less amps to produce the same amount of work (moving you down the road).
Less amp draw will help increase range. If you have two battery packs of the same total amp-hours, one with more small batteries, run in series for a higher voltage, will have better range.
That may also help you fit more batteries into the cycle frame because the smaller size is more flexible.
Notice on Rev. Gadgets bike how MANY batteries there are.
Hope that helps!
-Ben