They claim 99.2% efficiency (in lab conditions) and compare that to 97% for a chain drive. In lab testing, bicycle chain drives have been found to be 98.6% effi

They claim 99.2% efficiency (in lab conditions) and compare that to 97% for a chain drive. In lab testing, bicycle chain drives have been found to be 98.6% efficient: https://web.archive.org/web/20080306054536/http://www.jhu.edu/news_info/news/home99/aug99/bike.html https://web.archive.org/web/20080306054536/http://www.jhu.ed... so that would be an improvement of 0.6% rather then the 2% quoted..