The first major professional bicycle road race in America since the turn of the century, when every self-respecting city had a velodrome and presidents turned out for bicycle parades, is on its way to Washington.

This Sunday at about 3 o'clock, 75 of the world's best cyclists will wind up a 275-mile grind at the Mall, where $100,000 in prizes -- the richest purse ever pedaled for -- will await them.

For most of us, the race will be a blurred spectacle, a frenzied dash of anonymous cyclists. While balancing on two wheels is still a favorite leisure-time activity here, the gaunt faces you'll see during the furious final laps around the Tidal Basin and Mall will show why bike racing is considered one of the world's most grueling sports.

Who wins, and who's ahead at the end of each day's racing, are complicated affairs that only a computer and photo-finish equipment can determine. The fastest times for three days of racing determine the main winners. Sprints held at predesignated places -- two in each day's racing -- provide bonus time points, and a special 9.3-mile "time trial" Saturday afternoon in Richmond in effect adds a fourth stage to the race. Penalty points are also levied for such infractions as blocking another rider during a sprint.Awarding the $100,000 in prize money is even more complicated.

If this race, rather grandly named "Tour of America," is a success, it may be extended next year, perhaps to four or five days and into the Blue Ridge Mountains, says Robert Ingraham, vice president of World Tour Cycling, a New York sports firm that organized the race with Tour de France officials.

The National Park Service is the official host, with help from the Virginia and District governments. Peugeot, the French auto and bicycle company, is the major sponsor andfinancial backer.

Three teams of U.S. professionals have been created for the Tour, but like most of the other 12 teams, they may contain riders from other countries.

With six teams, France has the most riders in the race. Italy has three and the Netherlands one. Most teams have riders from several lands, including Australia, Belgium, England, Germany, Ireland, Norway, Scotland, Sweden and Switzerland. The final roster of riders usually isn't known until just before race time.

Most of the cyclists flew in during the week, fresh from spring races in Europe and accompanied by more than a dozen European journalists and a French television crew that will show the entire race to bike-crazy French TV audiences.

While the race will feature many men who are household names in Europe -- de Vlaminck, Winnen, Anderson, Herety, Biondi, Van Impe, Contini -- it will apparently be without last year's best-known name in cycling, Bernard Hinault. The four-time and 1982 winner of the Tour de France, Hinault was brought over for the announcement of the Tour of America last fall. But last week French racing officials insisted that Hinault, considered something of a national treasure, remain at home and ride in a French race this weekend.