Energetics of elite bicycling

We're pretty much obsessed with the Tour de France here. Today, Gina Kolata writes about the energetic cost of endurance:

By studying four racers as they rode in the 1985 Tour, Klaas Westerterp of Maastricht University in the Netherlands concluded that their metabolic rates increased 4.3- to 5.3-fold. That sort of increase in metabolic rate, he added, is what birds reach when they fly and is thought to be a physiological limit.
David Gordon Wilson, an emeritus professor of mechanical engineering at the Massachusetts Institute of Technology and author of "Bicycling Science" (MIT Press, 2004), calculated that Tour riders generate 400 watts of power when they are riding up mountains or trying to break away from the pack. An average person riding a bicycle and working as hard as possible puts out 150 to 200 watts, he said.

It's the most exciting race for the last several years, with many riders still in contention as they head into the Pyrenées.