Often, electric motorcycle design restrictions are..

2 yrs

Often, electric motorcycle design restrictions are lifted simply because the packaging of an electric motor can be smaller than that of a bike engine and transmission. Take a look at the Sondors Metacycle, which looks like something out of Blade Runner. Additonally, the range of electric bikes is roughly equivalent to their gas sibling. For example, a Harley-Davidson Livewire will do about 140 miles on a charge, and a new Ducati Monster will do about the same.
http://www.dbaoescooter.com/electric-motorcycle/