Nowadays, the world is more and more crowded with cars, which as a consequence, gives rise to more and more severe air pollution all around. It is time to come up with solutions to improve the current situation—thus electric bicycles are gaining more and more popularity. There is no doubt that electric bicycles are eco-friendly and healthy, but at the same time their speeds and efficiencies are limited. In order to well improve this problem, we will be engaging in studying the efficiency of the powertrain which is already existing in electric bicycles today. In the end, we would compare the efficiencies in different conditions, and figure out the most ideal efficiency situation.