Six men and a woman circle their bikes in the basketball courts outside T.T. Minor Elementary School on Capitol Hill. Their concrete playing field, no bigger than a tennis court, is hemmed in on each end by four orange construction cones, each marking a goal 5 feet wide. A few of the men stand on their pedals, their backs hunched, their knees locked in center. Others sit back, one hand on their handlebars, the other clutching scuffed, homemade mallets made of PVC pipe and old ski poles.

This is the face of Seattle Bike Polo — a motley group of bike messengers, bike-shop employees, nine-to-fivers and business owners. They meet two to five times a week to play bike polo, a relatively new urban sport that crams street hockey, polo and rugby onto a teetering bike seat.

On this Tuesday, the game begins when someone drops a fist-size orange plastic ball into the center of the court and all six players — three against three — descend upon it, circling, vulturelike around their prey. There's a scuffle and the sound of PVC pipe scraping against concrete, grunting, metal-on-metal. Laughter. Panting.

From a distance, you see only a tangle of spokes and pedals and mallets — a scrum of wobbling, three-legged beasts: two wheels and a stick — no feet are allowed to touch the ground. When the ball skitters from the nest of bikes, two players sprint after it, their mallets leading like lances. Knights without armor, on wheeled steeds.

A defensive player holds his ground and there's a collision; a bike falls over, spilling its rider onto the pavement. A mallet bounces across the asphalt; the ball lurches through the cones.

Goal! Goal! Goal! Then laughter, handshakes and the game resumes.

It goes on like this — the first team to get five points wins. Then it's repeated with new players until it's too dark to see. When it's over, this crew of amateur bike-polo players leans into the twilight, exchanging good-hearted insults and stories of battle wounds and bikes destroyed and improbable goals.

While bike polo — or "cycle polo," as it's sometimes called internationally — was invented by an ex-polo player more than 100 years ago, the sport has begun to take root in the urban centers in this country the past couple of decades. Most of the top players in Seattle — such as Soren O'Malley, of Montlake Bicycle Shop — began playing only four years ago, when small groups of bike commuters and messengers started to gather for games after work.

In the past couple of years, these informal clubs have begun networking via club Web sites and MySpace pages with their national and international brethren from Bangkok to New York. They exchange tips, compare rules and — most important — organize trans-city invitational tournaments.

In July, Jared Sessions, who runs seattlebikepolo.com, helped organize Tour de Polo, a massive informal tournament. Teams from Seattle, Portland, and Victoria and Vancouver, B.C., squared off in the two-day bracket.

Next year, Seattle Bike Polo plans to organize a national competition, luring teams from Boston, New York and Chicago to Seattle, Sessions says.

"It's just about to get really big," says Drew Anderson, a fruit seller who's been playing for about a year. "You keep hearing about the scene expanding all over the country, and it's true. People will come around and ask about it and more and more people are showing up."

Like any largely nonfederated sport, bike polo is played differently in different cities and regions. On one end of the spectrum, there are competitive bike-polo teams with formal rules that emulate horse polo. They play on grass fields with wooden mallets.

On the other end, there are the leaderless urban clubs — such as Seattle Bike Polo — that meet in parking lots and schoolyards, and play with a looser set of guidelines. They play with mallets made of broom handles and PVC pipe that are held together by bolts, glue and sheer will.

Bike-polo bicycles vary as well: Some use road bikes and mountain bikes; others prefer kids' bikes with 16-inch diameter wheels. "It's personal preference," says Heather Loop, who organizes a beginners' bike-polo night every Monday. "You should see the people on mini bikes, shooting around like crazy. They get really into it."

Regardless, almost everyone recommends that you use a bike that you don't mind getting dinged up. Scrapes and "Taco'd wheels" (when the rim of a wheel bends in on both sides, in the shape of a taco) are the unfortunate common consequences of frequent collisions.

Dedicated players jury-rig their polo bikes by moving the brakes to the left side of the handlebars and sawing off the right handlebar entirely, to free up the right side of the bike for swatting, dribbling and whacking the ball.

Each region, both internationally and even within the Puget Sound area, has begun to develop its own style of play. When in doubt of the rules, Seattle players tend to appeal to "basic etiquette."

"You don't have to go back to your goal after you score, but it's just polite," Leon Ettelson says, then adds, laughing: "But, I mean, there are times when you're not being polite."

Loop, who helps coach girls and newcomers to polo on Monday nights, explains: "If you hook someone's mallet, then you can pull them off the bike and that's fair, I guess. But if you're playing with people who are learning, it's just rude. That's it. The rules change, depending. It's all about having fun."

Some of the folks of Seattle Bike Polo look forward to universalizing the rules and gaining legitimacy as a "mainstream sport," with sponsorship possibilities and city-funded fields, where clubs could practice and host tournaments.

"We haven't run into too much trouble playing in parks and stuff. We leave the courts cleaner than we found them," says Sessions. "But, look " — he gestures at two players dribbling the ball around each other in an impossibly skillful dance while sweat pools on their foreheads — "these guys are incredibly talented athletes.

"Bike polo is partly just something fun to do on a bike, but it's also a pretty intense sport. It'd be nice to see them get sponsored. Or go to the Olympics."

Haley Edwards: 206-464-2745 or hedwards@seattletimes.com