This documentary on motorcycles features some of the top riders in the field, including Steve McQueen.

In 1970, professional motorcyclist Mert Lawwill, the winner of the 1969 American Motorcycle Association's Grand National Championship, sets out to defend his title for another season. To be awarded the winner's "No.1" license plate, a cyclist must compete in twenty-seven national races held across the United States. Among the several hundred AMA members, less than fifteen have the ability to win the plate, including Lawwill, Jim Rice, Dave Aldana, Dick "Bugsy" Mann and Gene Romero. Lawwill, who lives in California, spends eight months on the road racing and averages 1,000 hours per year tinkering with his bike. At the Columbus, Ohio track, Lawwill slits his tires with razor blades for better traction and tapes layers of plastic sheeting over his face guard so that he can peel them off as they collect dust. When Lawwill's throttle cable breaks, however, he loses the race. A series of subsequent breakdowns dim Lawwill's chances of winning the championship, which will be awarded in Sacramento at the last race of the season. Among the tracks on which the racers must compete, the one in Daytona Beach, Florida is considered the "Big Daddy" of the AMA circuit because of its steeply banked sides, which when ridden at high speeds, subject the riders to an intense centrifugal force. Quite different from championship racing is the world of motocross racing in which riders such as actor Steve McQueen and motorcycle shop owner Malcolm Smith compete over rough and tumble terrain, through mud and over mountains, making motocross one of the most physically demanding sports in the world. Smith, whose favorite expression after completing a grueling ride is, "that was really neat," is considered one of the best. Smith also competes in the International Six-Day Trials in El Escorial, Spain, for which the racers cover more than 200 miles a day in six days, during which they must reach appointed check points at an exact time or be penalized. In addition to being faced with temperatures ranging from twenty to eighty degrees, and elevations stretching from 2,000 to 8,000 feet, at the end of each day, the riders must compete in special tests to earn bonus points. Although the European racers, who are paid a salary to compete, are favored to win, Smith bests them all. Back in the United States, Smith and McQueen enter the Elsinore Grand Prix, a hundred-mile race in which the riders must complete three loops that run from the town of Elsinore, into the foothills and back. Approximately 1,500 riders assemble at the starting line in the tiny town, and as the competition begins, Smith takes a commanding lead, passing some riders as many as three times to win the race. McQueen, who has entered the race under the name "Harvey Mushman," finishes tenth. Ice racing is probably the most esoteric form of competition depicted in the film. In Quebec, Canada, cyclists don leather masks to protect their faces from the cold and pepper their tires with two-inch spikes to create traction on the ice track, on which they reach speeds up to eighty-miles-an-hour. In Sacramento, the location of the final race of the Grand National circuit, only Aldana, Romero, Rice and Mann are in the running to win the championship. Mann, who has broken his leg in a previous race, removes his cast to compete. After finishing a heat, Rice spins out, crashing his motorcycle, and is carried to an ambulance. One hour later, as the main race is about to start, Rice steps out of the ambulance, climbs on his bike and joins the competition. Shaken by his injuries, Rice slips to last place, and after Aldana totals his bike and Mann catches his shoe in a hole and wrenches his foot, Romero wins the race. Placing sixth, Lawwill must relinquish his No. 1 plate to Romero. Later, in Salt Lake City, Smith scales the hill called the "widow maker," so named because its forty-five degree angle has prevented anyone from reaching the top. Although Smith fails to reach the peak, he becomes the only competitor to ride his bike all the way back to the bottom. Smith and McQueen join the California Mojave Desert race, held every Sunday, during which amateur and professional riders alike tackle a hundred miles of desert terrain, dodging rocks, mine shafts and desert brush. At the end of the film, Lawwill, Smith and McQueen forsake competition for the pleasure of taking a spin across the countryside to the ocean, where they fashion circles in the sand as their motorcycles crisscross the beach.