RIO DE JANEIRO (AP) — Olympic road cycling races promise to be a grueling, 6-hour showcase featuring everything from the sun-splashed beaches of Copacabana and Ipanema to the squalor of the nearby slums.

There’s the backdrop of historic Fort Copacabana, and the long, fast flats along the brilliant blue waters of the Atlantic. There are the harrowing climbs and brutal descents on slick roads twisting through jungle, and the jarring cobblestone sections that add a little spice and a lot of bumps.

Yes, the route itself could be the star of these Summer Games.

“It’s the hardest course I’ve seen in a single-day race,” said American rider Megan Guarnier, who made a special trip to Brazil just to scout the course. “It has everything in it.”

Even stray dogs, which have scampered out of the favelas during training rides and led U.S. rider Brent Bookwalter to describe his first Olympic experience as “wild.”

“It’s legit. It’s a fully diverse course,” he said. “The route is spectacular.”

Which is precisely the point. The road race has always been a showpiece of cycling, positioned first in the program and rolling off the morning after the opening ceremony.

The race at the Beijing Olympics in 2008 sent riders past the iconic Temple of Heaven, Tiananmen Square and portions of the Great Wall of China. Like the course in Rio, it then sent riders off into the countryside, though the elevation changes were nothing like they will face in Brazil.

Four years ago, the London Olympics course started and ended with the spectacular setting of Buckingham Palace. More than a million people lined the route, packing the climb of Box Hill in the green Surrey countryside, in a nod to cycling fever that gripped the country in the days after Bradley Wiggins won Britain its first Tour de France.

Now, it is Rio de Janeiro’s opportunity to shine.

“I’m surprised someone signed off on a course this hard,” New Zealand’s George Bennett said. “It’s hectic, it’s dangerous. There are slippery roads, patches of oil, difficult corners. It could send you home early. But it’s the kind of racing I like. I like the chaos.”

The chaos begins when the men roll off from the century-old fort Saturday morning. They will cover 236 kilometers (146 miles), more than any single stage of the Tour, and climb 3,600 meters (11,800 feet), on par with hard one-day races such as Liege-Bastogne-Liege.

The Olympic road race should be relatively quiet along the coast, then begin to shake out on the first of two circuits, a lumpy 25-kilometer loop the men will tackle four times. Riders then head back to Rio and begin the second sets of circuits, two-and-a-half laps dealing with the Vista Chinesa climb and its 10 percent gradient, before a fast finish near Copacabana Beach.

The women’s course is identical but with fewer laps of the two circuits.

The upshot of such an arduous layout is this: Some names even the most casual of cycling fans will recognize should have a rare opportunity to chase Olympic glory.

That’s because the difficulty of the course lends itself to riders who can handle the climbing of a three-week Grand Tour, rather than an unpredictable wild-card that often springs from nowhere on flatter layouts. So, count Kenyan-born Tour de France champion Chris Froome of Britain among the contenders, even though he’s had scant success in other one-day races.

“You have to give it all on the day. You have to be willing to gamble and take your chances,” Froome said. “The Tour is over and of course I am happy that I won, but now I’m here to think about the Olympics. The goal is to try to get a medal for Great Britain.”

Froome pointed to the Colombian contingent headlined by Esteban Chaves and Rigoberto Uran, Spanish star Alejandro Valverde and former Tour champion Vincenzo Nibali of Italy as favorites.

Other riders who excel on hard courses include Dan Martin of Ireland and Rui Costa of Portugal.

The quartet of Americans is expected to pace the women’s race Sunday with Guarnier joined by Evelyn Stevens, Mara Abbott and Kristin Armstrong. But the Dutch squad of Anna Van Der Breggen and reigning gold medalist Marianne Vos should factor, along with world champion Lizzie Armitstead of Britain.

Considering what they must traverse, whoever stands on the podium likely will have earned it.

“We’ve never seen a course like this,” Bennett said, “and probably won’t see one like it again.”

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