[http://active.typepad.com/.shared/image.html?/photos/uncategorized/55767285.jpg]The growing sport of cyclocross is an off-road circuit race ridden on modified raod bikes. Mud is a sort of founding principle, dating to the sodden winter ground on which European road racers first explored the new terrain in the early 1900s.

In cyclocross races, athletes ride laps around a course that is one to two miles long, powering over flat straightaways, grinding through bumps and soggy pits and portaging over obstacles. A few races have been known to even include flights of stairs. Mud accentuates the pain and increases the difficulty.

In the United States Gran Prix of Cyclocross last race of the season, spectators crowded along the course's toughest sections -- two quick, steep climbs up the hill, which was so soupy that everybody but the pros had to dismount and carry their bikes. Every time a pack of riders came up the hill, a chorus of cowbells and yells arose. Cyclocross in the much also draws a different breed of spectator. "It's a total cult following here," said Matt Slavin, a semipro rider who had taken the day off from racing and was wearing a pink wig.

Slavin added, "Every race, you want to vomit, you want to quit, your bike's not working, and then you come up a run-up and everyone's cheering and you get pepped up. As soon as you're done, you can't wait for the next race. It's kind of like a cruel drug -- addictive."