You might think riding a bicycle down a ski slope so steep, you hit 138.75 miles per hour and break a world record before tapping the brakes is one of the more outrageously dangerous things anyone could do. But, Éric Barone says, "it's not too risky."

It's an odd statement, given Barone's 2002 trip down a Nicaraguan volcano, the one where the fork on his bike snapped at 107 mph, hurtling him into a horrifying, near deadly crash. It's also understandable. If this is how you spend your time, at least some ignorance, willful or not, of what might happen if it all goes bad is probably necessary.

Barone, 54, is a career stunt man who's worked with the likes of Sylvester Stallone and Jean-Claude Van Damme. He's also got an insatiable appetite for speed when it comes to bicycles. In 1994, he set the speed record for downhill cycling on snow. In 2000, he did it again, topping out at 138 mph. If it weren't for that gruesome crash two years later, he probably wouldn't have needed 15 years to top the record again.

This record run, achieved on March 28 in the French Alps, started last summer, with 60 people working on the bike, the suit, and the track. The challenge was to balance aerodynamics and safety. They started with a bike made by Sunn, a low, long, and flat design—almost like a chopper motorcycle, says Marc Amerigo, one of the project's leaders.

The rear wheel measures 29 inches, the front 27.5. Stock tires were provided by Hutchinson, pumped up to four bars of pressure, to lift as much of the rubber off the snow as possible, reducing friction. The front fork is thin to cut wind resistance, but strong enough to hold up at speed.

Once the team had the bike more or less together, they put Barone in the seat and 3D-scanned the whole thing. That provided the basic info they needed to work on the most important element: the aerodynamic fairings that would help the bike slice the air.

The team used computer-aided design to test 50 setups. Once it nailed the design, the team built the carbon fiber fairing and bolted it to the bike. Barone also wore what looks like a plexiglass bell over his helmet to further reduce wind resistance.

Of course, Barone's suit is specially designed for this task, with fairings in the arms and legs. It's made of rubber, so tight he can barely move (that's why he looks almost decrepit mounting the bike in the video above).

Flapping loose clothing can be annoying on a bike ride around town. At 130 mph, it can be deadly: Anything that could mess with Barone's balance was unacceptable. That's why, while the bike has pedals, Barone didn't use them. The gravity was more than enough to accelerate, and the risk of shifting weight isn't worth the added speed. That's also why his teammates didn't give Barone a push to get him started: too great a chance of tipping him over.

The first 300 meters of the track were bumpy, adding to the danger of Barone's ride. Richard Bord

Once the suit and bike were ready, the team put Barone in the wind tunnel, happy to find that their computer modeling delivered the aerodynamic numbers they were hoping for. "It's about the same approach as Formula One," says Amerigo, or designing a plane.