14th Annual Smithsonian.com Photo Contest
Sustainable travel options in Denver
A bicycle's performance, in both biological and mechanical terms, is extraordinarily efficient. In terms of the amount of energy a person must expend to travel a given distance, cycling is calculated to be the most efficient self-powered means of transportation.
© Nicolas Vasquez.
All rights reserved.
||Nov. 30, 2016, 11:18 p.m.