Stephanie Tuel writes:

The 18th stage was an excellent example of game theory at work. Lance Armstrong and the peloton were a few minutes back of a breakaway group of 6 riders (none of whom were a threat to the top of the overall standings since all were over 1 hour behind). Reading the various news reports and between the lines it appears that Armstrong’s team, US Postal, was doing all the work at the front of the peloton and the team of the closest competitors, T-Mobile, were loafing. (The crucial strategic variable in bicycling appears to be the effect of wind resistance, especially on the flat and on downhills–whoever is at the front has to work harder, and whoever is following can choose to conserve energy or share the effort.)