On a Saturday night in January, two hours before the first chute opens in front of a capacity crowd of 16,000, the 35 best bull riders in the world are pulling out their blunted spurs and leather chaps and working rosin into their braided rope riggings in the visitors' locker room of New York's Madison Square Garden. Chase Outlaw (yes, that's his birth name), a baby-faced cowboy from Arkansas with a patchy mustache, approaches the young Brazilian rider Emilio Resende, who wears braces on his teeth and a starched Western shirt the hue of Mr. Bubble, but with the logos of Cooper Tires and Wrangler jeans embroidered on it.

"That's a niiiiiice pink shirt," says Outlaw, buoyantly. A couple of American riders laugh. One of them is eating concession-stand pizza. Resende shakes his head, making it known that he doesn't understand. "I said, 'Do you like pussy?'" This time Outlaw makes a crude triangle-shaped gesture with his thumbs and pointer fingers to intimate the subject of his question.

Resende cracks a smile, but whatever humor there is in the moment is lost. All that's left is the gulf that exists in the bull-riding ranks between a group of jocular American cowboys accustomed to the lights and beer bashes and "buckle bunny" groupies that follow bull riding's top tour – and the growing group of serious-minded Brazilian riders kicking their ass.

In the 20-year-old Professional Bull Riders series, the richest in rodeo, there have always been Brazilian riders. The country is home to more than 200 million head of cattle, after all, so the talent pool is deep. The series' first champion was Brazilian Adriano Moraes, who won in 1994, and his countrymen are now enjoying unparalleled success in the sport. Four of the past five world titles are held by Brazilians. Seven of 2012's top 10 riders are Brazilian. The PBR's defending champion is Silvano Alves, the first to win the gold buckle back-to-back in the league's history.

So why the Brazilian dominance? Ty Murray, the league's co-founder (and a bull-riding legend in his own right), says they've just got an abundance of an old cowboy fundamental: "In our sport, grit is a prerequisite, and these guys have a lot of it. It's like being tall in basketball."

In the locker room, the Brazilians' abundance of grit isn't immediately clear, but their camaraderie is. American cowboys are scattered in ones and twos across the room, chatting as one of their iPhones plays a tinny "Enter Sandman," but the Brazilians form a tight group talking shop in the corner. Intermittent singing in Portuguese breaks out. Alves leads his three-year-old daughter, Hanyelle, by two hands as she walks gingerly across the room, an adult-size cowboy hat covering her eyes. Robson Palermo passes around sugar-free beef jerky and pounds his countrymen's chests, saying it'll make them strong. Twenty-seven-year-old rider Agnaldo Cardozo, head down, clutches a rosary.

"We're close. We drive together, we take planes together, we train together," says Guilherme Marchi, who at age 30 is one of the group's elder statesmen. Bull riding is a solitary sport with a steep logistical learning curve: Riders still book their own flights and are guaranteed just $400 for showing up each weekend. Add a language barrier, and the Brazilians' collaborative efforts seem essential. While the Americans scatter to their respective hometowns across the country and see one another only on weekends, a majority of the Brazilians return to Denton, Texas, where they live on a few of the older riders' ranches and train together during the week.

I ask Marchi if the Brazilians have a different approach than the Americans. "We ride more strong. We push more. We love the bulls that buck harder," he says. According to Marchi, the current stock of bulls play to the Brazilians' style – they are, by the numbers, bigger and faster than ever, thanks to extensive genetic and bloodline research.

There is only one piece of equipment – a rope rigging – that keeps bull and cowboy together for a furious moment. Each rider supplies his own, and as he countermoves to stay on an animal for the eight seconds required for a point-scoring ride, one gloved hand is all that can be in contact with the rope. The Brazilians wrap it around the bull's chest in the opposite direction than the American cowboys do, resulting in more support for the hand. A few cowboys, including Luke Snyder, have switched rope styles in search of some of the Brazilian magic. Others, like Ben Jones, have tried the Brazilian style, only to switch back. But Murray largely discounts that the Brazilians' equipment gives them an advantage. "At the end of the day, it's just a rope you use to try and hold on," he says.

The real difference between the Brazilians and the Americans, Murray says, goes back to fundamental toughness. "These guys," he says, pointing to the Brazilian corner, "train harder during the week. They don't whine, they don't bitch, and they come in here expecting to win. If I was a young rider, I'd park my bag in the next locker over and learn everything I could."

A big part of that drive, Murray says, is that many of the Brazilian riders come from poverty. "To say that some of these guys come from modest means would be the understatement of the year. I don't think most Americans can fathom it." The first Brazilian champion, Adriano Moraes, grew up in a house with dirt floors. Palermo, one of the best Brazilians currently on tour, comes from a town in the Amazon basin called Bujari, where there is one paved road. The home he grew up in didn't have electric lights until 2009. Like many of his countrymen, Palermo was working with livestock on a ranch by age nine. By 14, he was riding full-size bulls; a year later, he was winning modest prizes in local events.

The PBR's growing purses are obviously a motivating factor. Alves took home nearly $1.5million last year. "The young Brazilians come in hungry. They come to win the buckle. They want that money," says Marchi. "The American guys are here to have fun. We Brazilians go out, sure, but those guys party all the time."

One of those Americans is Outlaw, now in his second year in the PBR. After admitting to his fair share of good times on the circuit, he pauses a beat when asked about the Brazilians. "They're here to handle business," he says. "They take care of it every weekend."

The cowboys would eventually leave the locker room to put on a show in the dust under the lights, in front of a screaming New York crowd. To win, Palermo outlasted a honey-colored, 1,500-pound beast named Whitewater Trouble that spun like a cyclone. A Brazilian took the buckle and a check, an event that will surely repeat itself until the 18-city tour concludes in October.

Says American rider Snyder, "What it comes down to is, we all respect tough rides and good cowboys. You can't help but respect the Brazilians. Anybody that has a bad word to say about 'em .... Well, I chalk that up to jealousy."