The 'frog eBike 2012' by Jin Seok Hwang is a concept for a motorcycle that is completely electric and far too futuristic for today's streets.
Where a normal motorcycle would have a bulging engine, this bike has a hole, which Hwang says is a "symbolic void." Underneath the void lies the bottom chassis which is where all the battery cells are stored. To charge them, one must plug the bike into a charging station and wait for the battery cells to become full. By putting the battery cells under the void, it makes the bike extremely balanced and creates for a smooth ride.
Without having to deal with an engine that runs on fuel, Hwang was able to cut out a lot of chunky parts making for a sleek design.