A couple years ago, Andy van Bergen came limping into the office after one hellish beast of a Sunday bike ride—some 180 miles and nearly 23,000 vertical feet of climbing. “It crucified me,” he says. “It was the hardest ride I’d ever done.” His coworkers asked him what he’d gotten up to over the weekend. When he told them, the response was underwhelming: That’s nice. So what else did you do?

“I'm like, Are you fucking serious?”

Van Bergen, the 36-year-old founder of the Melbourne, Australia, cycling club Hells 500, knew he needed to come up with a bigger goal, the significance of which even non-cyclists couldn’t miss. Soon van Bergen, long inspired by mountaineering stories, had his answer. He’d pedal 29,029 vertical feet—the height of Everest—in a single ride. And he’d challenge others to do the same. Which is how the Everesting challenge was born.

The rules are diabolically simple: find a hill, climb, and repeat until you’ve conquered your personal Everest. No sleep allowed.

"I had this kind of sick feeling in my stomach," van Bergen recalls, "because I knew it was so appealing but so ridiculous. It was just eating away at me."

As far as anyone knows, credit for the first successful Everesting attempt goes to cyclist and mountaineer George Mallory, grandson of George Mallory, the British mountaineer who disappeared on Everest with Sandy Irvine in 1924. Seventy years later, the younger Mallory was training to climb Everest himself and rode 10 laps up Mt. Donna Buang, a 4,000-foot peak in the Victorian Alps.

“Riding Everest on a bike and climbing the mountain are substantially different, of course,” says Mallory, who at 56 has the third fastest known ride. “Everest by bike is, in my experience, physically harder than any one day on Everest.”

“I’d convinced myself that the sun was never gonna come up again,” Stanbrough says. “Every leaf in the road was a rock I’d have to dodge. All the twigs looked like snakes wriggling around. It was trippy, man."

When van Bergen got wind of Mallory’s ride in 2014 through the website CylingTips, where van Bergen works as a business developer, he made the undertaking an official Hells 500 challenge. Club members regularly spend winters coercing one another out of bed on cold, dark mornings to train for annual, Herculean trials like the group’s 500-kilometer (311-mile) initiation ride or the ludicrous entry into the “High Rouleurs Society”: 32,800 feet of climbing with a 36-hour cutoff. Riding Everest in a day was the next logical step. Club members who conquer the challenge now earn a grey stripe on their jerseys to mark their official badassery.

Everesting, though, was always meant to be inclusive, something anyone could do anywhere, on any road with tangible rise. And it caught on, first in Australia, then in the UK and finally in the U.S. last summer where fewer than 100 riders have accomplished the ride. To date there are 839 successful Everestings around the world, including repeats from a handful of elite riders.

In terms of physicality and mental taxation, Everesting is to cycling what mountainous ultras like Badwater or Hardrock 100 are to running. It’s a covenant of suffering.

"It's something that can just wither away any bit of strength you might have thought you had,” says Whitney Stanbrough, Tennessee’s first Everester. “You might think you're not gonna cry. You might think this can't beat you. But then you try it.”

Stanbrough, who works for the MOAB bike shop in Murfreesboro and regularly ticks off grueling endurance rides, found himself losing touch with reality deep into the night on his second attempt last Labor Day. “I’d convinced myself that the sun was never gonna come up again,” he says. “Every leaf in the road was a rock I’d have to dodge. All the twigs looked like snakes wriggling around. When I would get off to fill up my bottles, I would hear people snoring in the woods. It was trippy, man. It was absolutely mind blowing."

By the end of the ordeal the next afternoon, Stanbrough was lying in the road projectile vomiting, hands and feet numb. He’d developed ulcers in his mouth and couldn’t eat for days, couldn’t even celebrate with friends over a few beers.

It’s hard to imagine that the body appreciates such a thrashing. Given the consequences, is Everesting even safe?

“It's utter folly,” says Dr. John Mandrola, a cardiac electrophysiologist and a cyclist. “But that's why endurance athletes like it. The dumber shit is, the more they like it.” True, it’s how we push boundaries, how we test ourselves, figure out what we can’t do, then grow until we disappear the can’t. Everesting is just the latest trajectory in that pursuit. “If Pheidippides hadn't died, we'd all be running 10ks rather than slogging 26.2 miles,” Mandrola acknowledges in a twist of roguish medical nihilism. “Life is short, so, if people want to do dumb shit, doctors should let them, and then patch them up afterwards.”

Ultra endurance cyclist Andrew Kulmatiski posted the second fastest American Everesting (and fourth fastest overall) in October in 10:48:00 on northern Utah’s West Short Divide. Kulmatiski, 42, agrees with Mandrola’s “endurance athletes love dumb shit” thesis, but defends that quest, too, as a matter of perspective. "Yeah, I don't think it's healthy,” he laughs over a freshly broken rib suffered early in Zion’s 25 Hours in Frog Hollow mountain bike race. “But it depends on how you do it. There's people who do it on 100-foot climbs, there's people who do it on 5,000-foot climbs.”

That choice can make a huge difference. "Some of them sound ridiculous, and some of them sound okay,” van Bergen considers. “Haleakala, beautiful climb in Hawaii? Yeah, I could punch out three of those suckers. Then you hear about someone else: You gotta do 600 reps, are you insane?"

Take John Davis, 61, a music professor at Berry College who posted the slowest time at just over two days and three hours with a staggering 683 reps on a city-block-long hill in front of his Rome, Georgia, home. But knowing his limits, he took an easy pace that subjected him to nothing more serious than sleep deprivation. “I’m one of those everyday [cyclists],” Davis says. “It’s part of my health routine, really. I was just in a kind of recovery ride happy spot, and I ended up going vertical somehow. I was surprised that I felt as good as I did getting up the next morning. I didn't need an ambulance or anything."

That’s not to say an Everesting attempt doesn’t require training, and Davis did his. It’s a serious endeavor that, to meet it at your best, calls for marathon-style pyramidal interval training in the months prior that, van Bergen says, should peak about two weeks before an attempt. While most Everesters tend to be hardcore cyclists that simply stick to their regimens grinding out big miles and long hours, van Bergen recommends a minimum of 10 weeks of dedicated training that includes a lot of repeat hill climbs for solid quads and the odd 10,000-footer to educate your psyche.

"You need your legs to get you to [17,000 feet,] and you need your head to get you the rest of the way. It really is a bit of a mental game," van Bergen says. He and the Hells 500 team officially partner with CrankPunk—i.e. ex-pro-cyclist-turned-coach Lee Rodgers—for detailed, Everesting-specific training plans whose formulaic rides are rooted in pedaling through the perceived rate of exertion scale.

“If you're not a professional cyclist, if it's not something you do 40 hours a week, it's gonna wreck you,” Stanbrough warns.

So why attempt an Everesting? The elder Mallory’s infamous “Because it’s there” retort falls short. For Everesters, there is no Everest. Or rather, the mountain is merely an idea. And it’s easy to begin—just you, your bike, the hill, and your Garmin. That universal appeal is part of the draw.

“I'm an athlete,” says ex-pro cyclist Scottie Weiss, who in October set the Everesting world record with a time of 8:58:31 on Roanoke, Virginia’s Mill Mountain. “I know I can ride my bike. But this is something I did not know if I could do or not, to be honest. So the first time it was, Can I do this?”

For most, that’s the only question that matters. There’s a sense of revelation in the very attempt. “I think it really is a ride where you can discover things about yourself and how your mind works,” says Davis. “It gives you plenty of time to contemplate life and its meaning.”