You see them on their mountain bikes, speeding downhill on a steep dirt path and you say to yourself, Sure, I could learn to do that.

Then somebody tells you they’re just practicing, and when you make your way to the real competition trail, with 12-foot jumps and boulders that rest on giant headlong slabs of granite, what you say to yourself is, No way a human being can take a bike over that.

But they do. Like one participant noted, “When you watch the top guys, it looks like a video game.”

This past weekend the top guys and gals from all over the world were at the U.S. Open of Mountain Biking, in Diablo Freeride Park, part of the Mountain Creek Ski Resort in Vernon. It is the largest downhill mountain bike event in the United States, with some 550 athletes from 41 states and 15 countries competing for $50,000 in prize money.

Canadian Steve Smith was the top finisher, racing down the 1,040-foot mountain in 2:36.737, about one second faster than world champion Sam Hill, an Australian. There were also professional women racers competing, and amateur men and women.

Aficionados look up to the big names. But the heart and soul of mountain biking is the amateurs who spend thousands of dollars on equipment and take to the rugged slopes with no realistic shot at beating the pros — but come back and do it again and again, whether in a tournament or just for the fun of it on weekends.

Like David Perry, who has been riding for 10 years but did not make the cut for the finals round. “The World Cup crowd showed up today,” he said. “You get into the Rock Garden section and the rocks get huge…you just can’t flow it. You try to keep up your speed but it just breaks you down every chance it gets.” He was not complaining. He was sweating and smiling with satisfaction. That day, in that little town in Sussex County, he was the center of the mountain biking universe.

You can bring your bike here; Diablo is open for mountain biking until November, when snow arrives and the skiers follow. Start on one of the easier dirt trails if you are new to the sport. Don’t take on the more challenging trails until you are ready. Either way, you’ll enjoy the ride.