The Tour of California rolled through my neck of the woods yesterday and I got to watch some high class cyclists power up the same hills that I've cycled many times. They made it look pretty easy too. Here's a view of the main pack, with the current yellow jersey holder nicely visible:

What I thought would be more interesting to show is what was happening to the rear, well behind the bunched group of riders:

Is this guy so thirsty he's holding back to grab a drink from a friendly car? Sure looks like he's grabbing a water bottle. But there's a little more going on. 

This close-up shows Gregory Rast, riding for Team RadioShack. He's just done the same thing as the first guy. Notice his back. Kinda lumpy and bumpy, no?

Here's a view from the rear. That jersey of his is stuffed with water bottles. And now he's got to ride like crazy to catch the main bunch up ahead. Why'd he do it? 

The answer is that he's what is called a domestique rider for the team. And it's a tough job to have. It's his responsibility to slow down, get water and/or food from the team car, and then catch back up and distribute the goods to the rest of the guys. That way the riders who are viewed as having the best chance for victory can stay up near the front in case a breakaway happens and conserve their energy for the later portion of the race. 

Gregory is working his butt off and almost certainly hoping that at some point he can move up the ranks, leave the water duties to someone else, and go looking for glory. But for now he's most definitely killing himself for the good of team.