Originally Posted by
mr_pedro
Hence my question. In the video the energy required to spin up a free standing wheel is close to nothing compared to what you need to make a difference on the road.
As stated, a light spring was used to in the video.
See competing design: (much heavier)
EPA, working with the University of Michigan
http://www.epa.gov/oms/technology/research/research-hhb.htm