They scooted around 180-degree turns, leapt over railroad ties and raced through volleyball court sand pits that had been raked over to cause the most problems.
And all of that was when the cyclists were off their bikes.
Hundreds of cyclists and biking enthusiasts descended on Druid Hill Park yesterday for the third annual Charm City Cyclocross - an event that blends off-road bike racing with a series of obstacles that force riders to dismount and run with their bikes. With a tangle of red and yellow tape marking off the course, the route wound through the park and across dirt, pavement, a baseball field, grassy hills, sand and the bumpy roots of some gigantic trees.
"It hurts a whole lot, but it's a lot of fun as well," said Seph Coats, 33, of Alexandria, Va.
The sport is often referred to as the steeplechase of cycling.
It began in Europe in the 1940s as a way for cyclists to stay in shape and minimize their time on the bike during the winter.
Each race lasted only 45 minutes compared with the hours-long races in traditional road cycling. And the obstacles forced riders to slow down - reducing the windchill - while jumping off and on their bikes to hop over small fences and other barriers kept them warmer than riding alone would.
Cyclocross made its way across the Atlantic to the United States in the 1970s and has been increasing in popularity ever since, said Kristopher Auer, a buyer with Joe's Bike Shop in Mount Vernon.
"Now," he said, "it's huge. By cycling standards, anyway. Not by traditional sports standards."
The race is short compared with the 100-mile or longer events in which road cyclists routinely compete. But that doesn't make it easier.
"Forty-five minutes of a cyclocross race can feel even harder than a two- or three-hour bike ride," Auer said.
The Baltimore race grew out of a weekly cyclocross skills clinic that Auer taught. The first competition in 2005 attracted 220 riders, he said.
This year's event drew about twice that number of competitors, including several professional cyclists from Italy.
Riders described the course variously as fast, challenging, technical and a load of fun.
There was a series of S-curves that forced riders to dismount just before a steep incline marked by two 16-inch yellow barriers that had to be jumped. There was a pair of railroad ties encircling a tree in the park's wooded area, requiring riders to jump off their bikes, hop one stack of railroad ties, run around the tree, jump the other railroad ties and then leap back on their bikes while riding downhill. And there were wheel-stopping sandpits where the park's volleyball courts normally can be found.
"We tilled it up real good," Auer said. "That makes a rather unrideable sand pit."
The event attracted a significant crowd of spectators - many of whom brought cow bells and drums to cheer on the racers.
Lizuca Coats, 34, came out to support her husband of nine years, who earns a living as a musician with the U.S. Navy band. Their two daughters - 4-year-old Ariana and 3-year-old Natalie - took their jobs as bell ringers seriously.
"It's fun. I always admire that he has the will to go on," Coats said with a laugh. "He gets quite dirty and sweaty out there and thinks it's just great."
Seph Coats - his face caked with dust and his cycling jersey soaked with sweat - couldn't have agreed more.
"You race on the road all the time, but this is addicting," he said of his third year of cyclocross. "It's like playing. It's like you're a kid again."
Rosa Sovek, of Centreville, Va., had three cyclists to cheer for yesterday. Her husband, Chip, 38, has been competing in cyclocross races since he was a teenager. Now their sons - 7-year-old Nate and 5-year-old Ben - also compete.
Rosa Sovek, meanwhile, serves as the family's pit crew, cheering squad, chef and masseuse.
"The best thing about cyclocross ... is that you can see a lot of the course and a lot of the action," she explained.
Kathie Watkins, of Roxborough, Pa., came to watch her 37-year-old daughter, Lynda Maldonado, compete. She said she worried when her daughter explained the rules of cyclocross competition.
"Road racing was one thing. And to watch her race, there were quite a few accidents," Watkins said. "She had quite a few falls, and she's broken quite a few bones. But this is just brutal. It's brutal just watching it."