"This peculiar physiological effect, common to all high-concentration pursuits, may be why one finds among motorcyclists a large number of people who always feel as if there were a fire lit under them when they are sitting still. When they're out riding, the wind disperses the flame so they don't feel the terrible heat."
—Melissa Holbrooke Pierson, The Perfect Vehicle
The Perfect Vehicle is probably one of the best books ever written about the 'why' of motorcycling. Probably because it was written by a woman.