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24th of October 2018

Automotive



The Exquisite Balancing Act of Riding a Bike at 184 MPH

On Sunday September 16, 2018, Denise Mueller-Korenek broke the bicycle land speed record of 167 mph, hitting 183.932 mph at Utah's Bonneville Salt Flats. This story about the engineering and logistics behind this crazed effort originally ran on Thursday, September 13.

When you’re trying to become the fastest self-propelled human on the planet, you wouldn’t expect getting going at all to be the hardest part. But Denise Mueller-Korenek rides a bicycle so intense, even she can hardly pedal it. At least, not at the speeds hit by any sane cyclist. Once she’s going Autobahn speeds, though, she can unhook from the drag racing car that tows her off the line and start to crank the gear around. Drafting off the steadily accelerating racer and spinning up the rpm's on the bike’s compound reduction gear, she’ll have two and a half minutes to reach the goal that brought her to Utah’s Bonneville Salt Flats this weekend: set the motor-paced bicycle land speed record. Which right now stands at 167 miles per hour.

Accelerating past the takeoff speed of a Boeing 757 on a bike seems impossible, but a top-flight cyclist riding a remarkable bike and drafting the right vehicle piloted by the right driver can make it happen. That is, as long as everything—from physics to fitness, technology to team—works perfectly.

At 45 years old, Mueller-Korenek may be the ideal candidate. As a junior cyclist she won 13 national championships in road, track, and mountain bike racing, before anxiety led her to quit the sport. She spent the next 20 years running a business, raising three sons, skydiving, and racing Mini Coopers. She returned to bike racing five years ago and won two more age-group national titles. Even now, few men can hold her wheel when she opens up a sprint, says her coach, John Howard, who set a previous record, at 152 mph, in 1985. And she has the technical skills to match her explosive aerobic engine. “She’s a world-class bike handler.”

Howard, who coached Mueller-Korenek when she was a junior, got her back into the sport with a simple truth: No woman had ever attempted a speed record. “That was like a match to gasoline,” says Mueller-Korenek.

This weekend’s attempt comes two years after Mueller-Korenek hit 147.7 mph on her bike at Bonneville, setting the women’s speed record (by virtue of being the first woman to try it). She had planned to go for the all-time mark the next day, but thunderstorms rolled in, drenching the salt flats and nixing her chance. The speedy cyclist has changed a few details since, but the core of her approach hasn’t changed. It’s all about having the right equipment and the right team.

Pedal to the Mental

For a vehicle that will reach such eye-tearing speed, Mueller-Korenek’s KHS bike has the approximate aerodynamics of a chopper motorcycle—the wind-blocking car means the bike can serve other priorities. At 35 pounds and more than 7 feet long, it’s twice the size of a normal bike. The low-slung frame features geometry cribbed from the bike that Dutch cyclist Fred Rompelberg used to set the existing record at 167 mph in 1995. The walls of the hollow carbon-fiber frame tubes are three times thicker than those of conventional frames. The 17-inch tires were swiped from a motorcycle, since no cycling rubber is rated for anything near these speeds. A steering stabilizer and a custom-tuned suspension fork borrowed from downhill racing dampen irregularities in the unpaved salt track. The compound reduction gear—essentially two drivetrains joined together—is five times larger than a conventional racing bike’s top gear. That’s why pedaling from a standstill is like trying to start a car in sixth gear.

At 35 pounds and more than 7 feet long, Mueller-Korenek's KHS bike has motorcycle tires and a compound reduction gear setup optimized for riding at triple-digit speeds.

Project Speed

Just as important as the bike is the car. Mueller-Korenek will draft an 800-horsepower Top Alcohol dragster—the same one Rompelberg used. It accelerates more smoothly than the supercharged Range Rover SVR she used in 2016, but its aerodynamic fairing creates a low-pressure draft pocket just 46 inches wide, leaving Mueller-Korenek little lateral maneuvering room. The woman working the gas pedal, however, hasn’t changed.

Shea Holbrook didn’t jump at Mueller-Korenek’s invitation to join her team in 2016. Then 26, she already had a résumé full of four-wheel racing experience. But this was different. “It’s one thing to put me in a bomb that goes 300 mph,” Holbrook says. “Here, I have someone’s life in my hands.” Then she and Mueller-Korenek got on the phone. “It was like we’d known each other for 10 years,” Holbrook says. “This was a meant-to-be friendship.”

That bond matters when a cyclist and driver are trying to go triple-digit speeds within a few feet of each other. “The physics of the draft mean we have to be in perfect harmony,” says Mueller-Korenek. She has to follow closely enough that the negative pressure pocket in the car’s wake helps pull her along. She calls it “the dance.”

The dance floor is the Bonneville Salt Flats, a 30,000-acre salt pan near the Utah-Nevada border, one of the few places in the world with the space and the flat, uniform surface needed for a speed record trial. The Short Course track is 5 miles long. After a few low(er)-speed practice runs, Mueller-Korenek will make as many record attempts as she can in the three-day window at this weekend’s World of Speed, sharing the track with car and motorcycle enthusiasts going for their own records.

To start the run, Mueller-Korenek is attached to the dragster with a tether. It’s a rough way to get going, but it works. “The faster I’m going the more stable I am,” Mueller-Korenek says. “If she drags me up slowly, I’ll fall.” Holbrook will feather the throttle to pull as smoothly and quickly as possible over the first mile, which should get her to 110 mph.

Then Mueller-Korenek will release the tether, and Holbrook will accelerate to around 130 or 140 mph, monitoring Mueller-Korenek’s nonverbal communications via a camera: nods to accelerate, head shakes to back off. A color-coded series of lights on the back of the dragster will show Mueller-Korenek how far they’ve gone, and how much track is left.

To secure the record, Mueller-Korenek—now pedaling around 110 rpm—will have to hold 168 mph between mile markers 4 and 5, where the timing traps measure her average speed. As Holbrook accelerates, the cyclist will push 700 watts for more than a minute to stay inside the draft pocket behind the dragster’s fairing. That’s about what a Tour de France sprinter produces in the final minute of a stage.

Any object in motion creates turbulence. But a bluff body, like this fairing, creates a series of alternating vortices that swirl in its wake. “There’s a back-and-forth sensation,” Mueller-Korenek says. As she drifts back, the oscillation feels like being pushed forward on a swing. “At 130 mph, it’s a little kid push,” she says. “Over 150, it’s like an NBA player giving me a shove.” Her job is to deal with those forces while keeping her 7-foot bike inside the 10-foot pocket of air. At 168 mph.

After a successful junior racing career, Mueller-Korenek left the sport for two decades. She sees this speed record attempt as an effort to make up for time lost—and show what she can do.

Project Speed

So it’s obvious things can go wrong in a hurry. If Holbook misses a head shake and Mueller-Korenek can’t hold the draft, the turbulence could force her into a violent crash. She’ll wear a motorcycle helmet, gloves, and a leather-and-Kevlar street-luge suit, but it’s no guarantee of safety. In 1988, seven years before he set the record, Rompelberg crashed at almost 150 mph at Bonneville. He broke 24 bones.

For Mueller-Korenek, though, the risk is worth it. This weekend’s attempt is about unfinished business. An opportunity, as she puts it, to “right the wrong” of how she left cycling for all those years. An opportunity to finish what she started in 2016. And the opportunity to occupy a rare firmament: a woman setting a record historically dominated by men. That’s what drew her to this quest, years ago, when Howard told her no woman had ever attempted it. “How often do you get the chance to be a pioneer, and do something that no one else ever has?”

This time, it’s not just something no woman has ever done; it’s something no one, period, ever has.

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