GANG OF TWO | Hugo Jezegabel, left, and Fred Jourden on their classically designed bikes in Paris. Photography by Francois Coquerel

ON A SPRING MORNING inside a cavernous Yamaha moto showroom in Paris, a sea of nearly identical modern-day scooters are parked in tidy rows, their inner parts masked beneath monochrome sheaths of metal and plastic. But hidden in the back, past the garage, something altogether different is happening. There, two friends—Fred Jourden, 38, and Hugo Jezegabel, 28—are making "bespoke" motorcycles by soldering together, pastiche-style, parts from their favorite vintage BMWs, Hondas and Kawasakis from the 1960s through the '80s. Their shop is called Blitz Motorcycles, and the address isn't listed.

Jourden and Jezegabel sell mainly by word of mouth to business professionals and, increasingly, members of the global cool set that share their passion for a nostalgic brand of manliness that privileges grease and gears over day-trading. Unlike the showroom scooters, all the mechanical elements of their bikes—colorful old engine tanks, spark plugs, accordion-like cylinders—remain very much exposed. The style is an homage to the golden age of motorcycles, one that's epitomized, for the duo, by the 1971 Steve McQueen cult biker documentary On Any Sunday.

Photos: Wheels of Fortune

Click to view slideshow Photography by Francois Coquerel

The two friends founded Blitz in 2010, but they've been customizing bikes for friends for the past several years, sourcing parts from swap meets and from Le Bon Coin, which Jourden calls "the French eBay." They make only about 10 bikes a year, with each working on four or five at a time over the course of several months. "To us, a motorcycle is two wheels, one engine—full stop," says Jourden. "It's all naked so you can appreciate all the parts. Each bike is unique. We don't 'industrialize' any part of the process." And even though they and their customers take the bikes as far as southern Spain or Norway, they're not built for speed. "They're made to hit smaller roads. What's the point of having a beautiful bike if you ride it at 300 kilometers an hour and nobody can see it?" Those old engines are repaired if need be, he says, but never "powered up."

Such devoted retrofitting comes at a price. Between the $15,000 for their retooling services, or what they call "artistic direction," plus the cost of an old engine and parts, their bikes can cost in excess of $20,000. Yet their reputation is growing. "During fashion week, we had so many visitors we couldn't get any real work done," says Jourden. "It was PR for us all week."

Public relations is something Jourden, who grew up outside Paris building remote-control cars as a kid, knows a thing or two about. Previously a marketing executive for Lycos (a popular search engine from the mid-'90s), he had a weekend love for riding his 1961 BMW R50/2. "I realized I was either going to spend a lot of money having it serviced or learn how to do it myself," he says. So he started taking mechanics classes at night after work. "All day long, I couldn't wait to get grease on my hands."

Jezegabel also grew up outside Paris, the son of a newspaper editor and a lawyer. (In addition to a lot of silver jewelry and a black onyx ring, he wears a vintage Timex compass watch with a grosgrain band.) Unlike Jourden, he's worked on bikes from an early age and has never held an office job. He lives with a friend on a boat on the Seine and at night is the social one, hanging out at Les Enfants de Paris, a restaurant and bar in the trendy Oberkampf area. But in the shop it's Jourden who does most of the talking, especially if the topic is the romance of hitting the open road on a bike with your buddies.

Jourden points to his own bike, a 1979 BMW R100/7 with a beautifully battered dark-blue, black-striped engine tank that immediately evokes Evel Knievel flying off a ramp into thin air. Jezegabel's bike, built around a chrome-plated BMW R80 engine from 1984, stands nearby, ruggedly mud-spattered from a trail race in the south of France. Jourden explains how the wires that clutter most contemporary bike fronts have been run ingeniously inside the handlebars, leaving one to admire the bike's clean, low-slung lines, painted in the handsome, scratch-proof matte black that distinguishes so many of their bikes. Pair those handlebars with a vintage '70s yellow headlight, vintage Firestone tires and a custom black leather seat, and you're looking at one impressive two-wheeler.

Inside the garage, located in the genteel, decidedly un-edgy 17th arrondissement, vintage maps adorn the walls while engine tanks hang from the ceiling. In a makeshift living-room area fashioned from mid-century furniture they salvaged from the street, the pair receives guests and would-be customers. "Bikers are the bad boys," explains Jourden. "I'm not a bad boy. I don't drink or do drugs, and I give my seat on the bus to an old lady. But on the weekends on my bike, I can be a bad boy, leave the moneymaking system and be free at 90 kilometers an hour. We're modern cowboys.

"When I worked for Lycos," he continues, "my grandfather couldn't understand what I did all day, which was send e-mails. Now he can."