When I began to ride a bike again four years ago I read about maintaining pedaling cadence at 90 RPM or more for efficiency. There was no explanation why high cadence would be more efficient than a lower cadence but I took it on faith that people who had been riding professionally for years knew what they were talking about. Just yesterday I came across an article that explained all. The basic idea has to do with the fact that muscles work like a rocket motor in that individual muscle bundles are either on or off. To generate a greater force, more muscle bundles are recruited. During a long ride, only a portion of the available muscle bundles are needed. Towards the end of such a ride, as muscles begin to tire, more muscle bundles are needed and recruited just to maintain the same speed and power output. This results in a higher heart rate which is known as cardiac drift. The cyclist is working harder for no more speed. High cadence recruits fewer muscles burning up energy during the ride and the end result is a rider who has more energy left at the end. Read about it here: http://velonews.competitor.com/2014/...-racing_318783 As a certified card carrying old guy, I need to conserve as much energy as possible so this article is particularly useful to me.