Bill Main, the co-owner of Segs in the City, leads a group of tourists on a Segway adventure along the National Mall. (McKenna Ewen/The Washington Post)

Segways don’t do wheelies, or Bill Main might be tempted to pop a few.

“At six-and-a-half-grand apiece, we discourage anything that might bend the wheels,” Main said as he prepared to mount one of his 55 Segways, a black-and-pink conveyance that looked like the offspring of a Big Wheel and an upright vacuum cleaner. “My best move is just staying on it.”

Still, it’s a heady time to be the Segway king of the nation’s capital. The Fourth of July weekend is typically a peak time for tour companies such as Segs in the City, which Main owns with his wife, Tonia Edwards. And this year the holiday comes just a week after the couple made a little history of their own. Because of their challenge, a federal appeals court knocked down a century-old law requiring hundreds of Washington tour guides to pass a test and pay a $200 fee before leading tours around the city. Even Segway tours, which Main contends are as much about the Segway as the tour.

“You don’t have to tell them who shot James Garfield because they don’t particularly care,” Main said of the customers who take his tours mostly for the novel experience of the ride. “What they want to know is, ‘How do I make this thing

go faster?’ ”

Bill Main, owner of Segs in the City, listens to a customer on July 2 in Washington. (Yue Wu/The Washington Post)

A decade after launching one of the first Segway tour companies in the world (Main and Edwards think a Paris shop beat them by three months), the couple has seen the futuristic vehicles become a sightseeing fixture in Washington. Six companies now send tourists whirring from monument to monument.

On Wednesday, Main prepared another group to set out from the Ronald Reagan Building, where his D.C. operation is based (he has other outlets in Annapolis and Baltimore). The lanky 70-year-old, who has a deep tan and tousled white hair, demonstrated the subtle knack of leaning forward and back to make the thing go, slaloming around the courtyard as smoking office workers looked on from the doorways.

Ann Breinig, a retired Pennsylvania teacher, lurched unsteadily on her first try. But Main, a Segway whisperer, put a calming hand on the handle bar — “Relax, relax,” he said in his laconic Australian accent — and soon she was zipping smoothly along, letting the gyroscopes do the balancing.

Most people master the machines in minutes, Main said. His company has about 10,000 riders a year and sees a minor spill once a month or so, he said.

He can remember five more-serious crackups in the past 10 years. “We have had to fish one Segway out of Baltimore Harbor,” he said.

Another first timer, a 25-year-old Spanish model named Marta Ponce, looked balefully at the pointy bike helmet before fitting it over her long hair. Main knows that what might be called the dork factor is a fact of the Segway biz. He hears from his customers of macho dads and too-cool teens who choose to stay by the hotel pool rather than parade along Constitution Avenue on something that looks like a Transformer pogo stick.

“Oh, there are people who won’t come on the tours just for that reason,” Main said.

Left to right, Jacob Wearin, Marta Ponce and Jason Wearin ride Segways in the bicycle lane on Wednesday in Washington. (Yue Wu/The Washington Post)

But now he sets out with a batch of the willing, leading a single-file line of Servo-powered ducklings, each of whom has paid $70 for the two-hour circuit of landmarks. Main began a spiel that he acknowledges is as much about entertainment as historic depth.

“If you know the Hope Diamond, you know it is a cursed stone,” Main said, speaking to his followers through Bluetooth earpieces as they rolled past the Museum of Natural History. Most of them seemed more focused on maneuvering up a sidewalk ramp than following his account of the Hope’s mysterious pedigree.

He tells the eight to 10 guides on his seasonal staff, most of them college students, that he doesn’t care what they say to the customers as long as they don’t offend or mislead them. If they dispense facts, the only rule is to dispense them accurately.

Jason Wearin, a bridge inspector from Washington state who was visiting the District with his son, said Main’s talk generally comported with the bus and walking tours they had already taken.

“It’s a little bit of the same information,” Wearin said as he rattled over the gravel path in front of the National Museum of American History. “I didn’t know that about the Hope Diamond, though.”

And the tour overall?

“It’s awesome,” he said. “I just love driving this thing. I’ve never seen one in Yakima.”

It may be that Segways, once touted as a revolution in personal transport, have become largely the purview of tour groups, mall cops and parking patrols. Main and his wife first latched onto them in 2004, when a retired airline pilot rode one into their Annapolis bike-rental shop and suggested they add a few of the machines to their rolling stock.

Main, who was born in Scotland and grew up in Australia, come to the United States in 1993 as a mobile telecom consultant. After retiring, he and Edwards, an Australian-born U.S. citizen, lived aboard a sailboat and in the Caribbean for a few years before coming to Maryland and opening the bicycle business.

At first, they simply offered Segway rides around the inside of their store for $5 a pop. But soon they had the idea of leading the curious out into the streets of the historic district. The Annapolis outings proved popular, and within a few weeks Edwards unloaded a vanload of the machines on a Washington street corner and conducted what the couple thinks was the capital’s first guided Segway tour.

Steering through Washington’s bureaucratic labyrinth was one of the biggest challenges. Nowadays, Segway guides know where to go (staying between the bollards and the curb at the Supreme Court) and where not (staying out of the parking lot at the Jefferson Memorial). But at first, Park Service and city police were baffled about where to consign these newfangled pedestrians with wheels.

“We had a lot of one guy saying ‘Get off the sidewalk’ and another guy saying ‘Get off the street,’ ” Main said. “But it’s all settled now. We have very few issues with law enforcement.”

What they did have was an issue with was the tour-guide law, which forbade leading a paid tour without a license. After being barred from giving tours of Gettysburg National Military Park (where Main said the couple took the historical details very seriously), they decided to challenge the similar restrictions in Washington. The libertarian Institute for Justice took the case in 2010, successfully arguing that the law was an infringement on speech.

“It’s very satisfying,” Main said. “We think we are on the side of right on this one.”

And so he trundled on with his charges as a legal tour guide at last, past the Washington Monument, the Tidal Basin, the Martin Luther King Jr. Memorial. After devoting years to the court challenge, he may have time to finish the application for U.S. citizenship he has been procrastinating on for years.

One reason for the delay?

“You’ve got to take a test for that, too,” he said.