Agreed. I have a 12ah battery myself and that nets me about 13 miles on motor power alone. (but I stop and charge after 10 miles to ensure the battery will last longer) Though mine can go to about 25MPH. But most of the time I am running it around 18 to 20MPH. So you'll need 15ah or higher to get 20 miles out of it.
Also mine is a mid-drive system which is known to be more efficient then hub motors. So you will probably get even less then that with a hub motor paired with 12ah battery..
I live in a small town so the battery is more then enough for me. But for you...definitely will fall short.
Last edited by Apache Thunder; 08-10-12 at 04:46 PM.