A cycle is the ultimate means of transport for short distances

A fact that nowadays all of the most popular energy sources are finite and a significant amount of them is harmful to the environment, makes me think about what means of transport is an ultimate one - the one that works regardless of any external resources, is the most simple and robust. In my opinion a vehicle that one can be cosidered so is a cycle, which for working requires only one source of energy - our muscles and enables to move relatively long distances, in relatively comfortable way, in relatively short time, for free. It is a vehicle that enable us to comfortably move around cities and get to suburbs relatively fast, what in case of cars is less smooth, more expensive and harmful to the environment.