AT 3:30 A.M. on a Sunday morning, 2,000 cyclists crammed themselves into Los Angeles’s Sunset Boulevard. The neon lights of the 24-hour Tang’s doughnut shop and a nearby McDonald’s cast a mustard glow on the street. It was March, yet even this early in the morning the weather was ideal—high fifties, clear skies, and not a hint of wind. The cyclists rode everything from commuters to $5,000 carbon-fiber road machines, and they came from half a dozen states and at least three countries. But mostly they were Angelenos—kids in tight-fitting jeans on fixed-gear bikes and roadies in Lycra with bulging calves. Soon there were 4,000, and I was one of them. After only three hours of sleep, I had pedaled down from Hollywood with five friends but instantly lost them all in the crowd. I stuck myself between a guy on a recumbent bike and a group of very serious-looking twentysomethings in matching jerseys.

“First time?” one of them asked, glancing down at my embarrassingly flashy carbon-fiber rental with flat BMX pedals and then up at my backpack. I nodded. “Good luck,” he said.

I was here to compete in the Wolfpack Hustle Marathon Crash Race, a 26.2-mile sprint through the L.A. streets in the early hours of the morning. Races like this one, unsanctioned and grassroots, are popping up across the country. There are hundreds of unsanctioned mountain-bike races in the U.S.—like the Leadville Trail 100 and the cross-country race at the GoPro Mountain Games in Vail—and countless road events, like New York’s Red Hook Criterium and Rapha’s Gentlemen’s Race series. They keep growing for two main reasons. One, organizers would rather avoid the bureaucratic hurdles—paperwork, insurance—put in place by USA Cycling. And two, participants are eager to change up the format. Prefer to ride at midnight? Go ahead. Want the trophy to be beer? Terrific.

IF YOU'RE A SERIOUS RACER, the consequences of competing in an unsanctioned event can be stark. In the past year, USA Cycling has threatened to enforce a long-overlooked rule banning members from participating in them, although to date no one has been disciplined. Races like the Leadville 100, a 100-mile mountain-bike race that takes place each August, may be unsanctioned, but the city goes overboard promoting it. Not only is the Crash Race not sanctioned by USA Cycling, but it also lacks city support. Speaking in technical terms, it’s illegal. But that didn’t prevent 4,000 people, including a handful of professional road racers, from showing up this year. After all, no race in the country, sanctioned or not, has quite the reputation for chaos and debauchery that the Crash Race does. It’s the world’s largest unsanctioned, unpermitted, and otherwise illicit bike race. And it’s only getting bigger.

It works like this. At 4 a.m., on the morning of the Los Angeles Marathon, race officials begin blocking off the streets. About 15 minutes later, the cyclists flood the start line. There are four categories: Men’s Fixed, Men’s Geared, Women’s Fixed, and Women’s Geared. The winner of each gets a set of military-style dog tags—a coveted possession in the L.A. racing scene. Unlike most other bike races, all categories ride together. Which can create problems, since fixed-gear riders and freewheel riders take turns differently. A fixed-gear rider must either pedal or skid through turns, forcing a drastically different line than a rider on a freewheel bike is likely to take.

To complicate matters further, the thousands of racers who gather are of vastly different ability—it’s a mess of commuters, hobbyists, weekend warriors, professional road racers, and, as one bike-shop employee put it, “fatties on fixies.” When the crowds are this thick, no matter the skill level, accidents are bound to happen.

And they do. Riders go down on every turn, straightaway, climb, and downhill. In 2012, people wrapped around light poles. A man went through the rear windshield of an SUV, reportedly requiring 26 stitches. One girl showed up at the finish line with her face covered in blood and missing two front teeth. Hence the name: Crash Race. “It’s mayhem,” a member of the Ritte Women’s Cycling Team told me before the start. “I mean, it’s fun—until you wake up in the hospital.”

Despite the dangers, the race has grown exponentially each year, thanks largely to social media and word of mouth. Two years ago, rumors circulated that the LAPD wanted to shut it down. There were only a few hundred racers at that point, but since it’s unpermitted and uninsured, and the riders blow through stoplights (there are at least three intersections left open to traffic at that hour), the cops had plenty of reason to take action.

That they didn’t is in large part due to Officer Gordon Helper, a 15-year LAPD veteran. The 41-year-old grew up racing bikes and, as a member of the department’s bicycle unit, was familiar with the city’s underground racing scene. He lobbied to support the Crash Race, making the argument that it would be more beneficial in the long run to work with the largely law-abiding cycling community than against it. Although the upper command has yet to endorse the race, 19 officers escorted the 2013 racers through the streets in the name of public safety.

Officer Helper has since become a minor celebrity in the community. He was even given a set of dog tags, a prize so coveted that each year the race seems to boil down to an L.A.-vs.-the-world effort to keep the tags in town.

Last year’s overall winner was Robbie Miranda, a 36-year-old former X Games BMX gold medalist who lives in nearby Huntington Beach. It was the first time the overall winner’s tags had been taken from the city.

Though Miranda was back to try and defend his title, the favorite this year was Fabian Vasquez, a slightly built 21-year-old who works at an L.A. bike shop and rides the city’s streets every day. As in any competition, Vasquez says, winning the Crash Race is 60 percent skill and 40 percent luck. And when you’re launching yourself down a road with 4,000 riders, luck is exactly what you need.

FROM 1995 UNTIL 2009, the Los Angeles Marathon officially allowed 10,000 riders to do a pre-marathon cruise along the looping 26.2-mile course, which started and finished just east of downtown. Then, in November 2009, former L.A. Dodgers owner Frank McCourt, who’d purchased the marathon 14 months prior, announced a new point-to-point course from Dodger Stadium, north of downtown, to Ocean Boulevard near the Santa Monica Pier. The bike tour “didn’t work within the new vision” of the race, an L.A. Marathon spokesman told me. So it was canceled.

“We took that as an insult,” says Don Ward, the de facto director of the Crash Race. So 25 riders decided to show up anyway—but instead of just riding the course, they’d race it.

A year later, word had spread and 400 cyclists came. It was clear the race needed someone to take charge. Ward was the obvious choice. At six foot eight and 220 pounds, he doesn’t look like a bike nut. And until nine years ago he wasn’t. But in 2004, a friend asked Ward to join her on an informal ride to a bar across town. He didn’t have a bike, so he rode his skateboard—18 miles. The next time, he had a bike. Pretty soon they were meeting once a month for what came to be called Midnight Ridazz. Aside from a relatively small Critical Mass showing, says Ward, there wasn’t much of an organized-ride scene in L.A. “Critical Mass was always about protesting cars,” he says. “We were just a fun ride to do at night once everyone got home from work. It turned out to be something that people really rallied around.”

He soon gained the nickname Roadblock, for his propensity to place his large body in the middle of intersections to hold traffic for other riders. Within a few months, the ride was attracting 2,000 people. So Ward made a website, MidnightRidazz.com, and encouraged people to start their own small-scale rides. (It was a huge success—to date, 7,000 rides have launched in the L.A. area.)

In 2005, Ward and some friends started a fast-paced Monday night event called the Wolfpack Hustle. (The ride is now led by Fabian Vasquez.) The mantra of Midnight Ridazz had been: Everyone welcome, on any bike. The Wolfpack Hustle’s became: You might get dropped. Ward was never dropped, but neither did he finish at the front. Yet, what he lacked in pure athletic ability, he made up for in charisma and organizational skills. It wasn’t long before he was the group’s figurehead and the Crash Race organizer. “I like creating spectacle,” he says.

In 2011, the Wolfpack Hustle received national attention during the closure of the 405 freeway, one of the main arteries through Los Angeles. When it was announced weeks in advance, panic ensued, and the media dubbed the coming apocalypse Carmageddon. In a fit of PR brilliance and environmental silliness, JetBlue announced that it would offer $4 flights from Burbank to Long Beach, a distance of less than 40 miles. Wolfpack Hustle challenged the airline to a race. (Ward did not participate, but had a hand in organizing the stunt.) The bikes left as passengers began going through security. The plane had barely taken off when the group of five cyclists arrived at the finish.

AT 4:20, Ward led the rolling start toward downtown along Sunset Boulevard. True to its name, everything went to hell the moment riders began clipping in. “Two fixed riders in front of me tangled, and the guy to my right ate shit,” said Evan Stade, a lanky 26-year-old software engineer, who finished second last year. “I was almost taken out twice in the first 30 seconds.” At Sunset and Echo Park, the official starting line, Ward broke away to hurry back to his car. Even in a car, he’d barely cover the 26-odd miles to the finish faster than the leaders.

From here the cops took over as our unofficial escorts, guiding the pack past Dodger Stadium and hooking a right into downtown. Far behind Stade and the rest of the leaders, I just wanted to survive. The twentysomethings in matching jerseys had vanished into the distance ahead of me. At every turn, I could hear carbon fiber and muscle collide with concrete as bikes went one way and bodies another. I rode as slowly and defensively as possible for the first two miles. Then something happened: I passed a group in Lycra who were struggling on the first hill, at mile four. What the hell, I thought, this is a race. So I gunned it.

The course isn’t particularly tough. The only other hill comes a mile later. But it’s the spot where the lead pack separates from the weaker riders who are a little too hyped up on adrenaline. In previous years, the hills whittled the lead pack to a dozen. This year there were 50. When Jo Celso, last year’s overall female winner, lifted her head at the crest of the second hill, she was the only woman left in the lead pack. There were 20 miles to go, but all she had to do was hang on and stay on her bike—easier said than done.

Celso’s body is lean and muscled and not much different-looking than many of the male racers. “As a woman, the more you ride, the more you look like one of the guys,” she says. Celso, who is 24, started racing in 2011. She was having a good season, riding fast and winning races. Then, in April of that year, she noticed a lump on her neck. It was Hodgkin’s lymphoma. It took eight months of chemotherapy and four more months of recovery before she was back to full strength—just in time for the 2012 Crash Race. Her hair is still cropped short from the chemo, which had caused some confusion when she won in 2012: Ward prematurely awarded the woman’s victory to another rider. It was an awkward few minutes before the mistake was corrected.

After the course passed through downtown, the race was largely a downhill shot to the beach. We rode together through Hollywood, where men in tight shirts and women in even tighter dresses were just leaving nightclubs. At the Whisky a Go Go in West Hollywood, we took a left before flying past the Gucci and Prada stores on Rodeo Drive. Which is when I realized that this was part of the draw: Who wants to drive two hours to race through an office park in Yorba Linda when you can scream down some of the most famous streets in the world?

As I rode through Beverly Hills, a spontaneous rendition of the Weezer song by the same name broke out around me: “That’s where I want to be!” Even though I felt like someone had strapped sandbags to my legs and punched me in the stomach, I couldn’t help but sing along.

FROM MILE EIGHT to mile 21, the leaders hung together in a tight group. They averaged a speed of only 26 miles per hour—slow enough to allow the inexperienced riders to stay with the leaders and prevent the group from spooling out into a safer, single-file line.

When they came around to San Vicente Boulevard at mile 22, John Wike broke off the front and quickly built a ten-second lead. Wike, a former pro, was one of the most experienced riders at the Crash Race. He and Miranda are teammates on Surf City Cyclery/Sterling BMW, a well-known Southern California team. It was a textbook tactical move: Miranda was one of the best sprinters in the field, and anyone chasing down Wike would force a sprint finish, all but guaranteeing Miranda the win. If no one chased him down, Wike could take the win himself.

Wike was leading all the way into the last turn, onto Ocean Boulevard. But Miranda, Stade, and two other riders were only four seconds behind and gaining fast. Vasquez, the hometown hopeful, was just behind them and in the top ten, riding at roughly 37 mph. He could see the leaders. But on the final turn someone went down in front of him, creating a pile of metal, carbon, and human that he couldn’t avoid. He flew over his handlebars and cracked his helmet, later receiving seven stitches above his eyebrow.

With 600 yards to go, Miranda began his sprint. Six hundred yards is a long way to drop the hammer, even for an X Games gold medalist. It was long enough that Stade could hang with him. They rocketed along the still-dark, palm-lined streets at 42 mph. With 400 meters to go, Miranda ran out of gas. The long sprint favored the taller Stade, who came around Miranda, put his head down, and cranked to the finish line. Fourteen seconds later, Celso crossed the line, repeating as the overall female winner, though it would be more than a week before she was formally crowned, thanks largely—again—to her short hair. Twenty-odd minutes later, I crossed the line.

The crashes didn’t stop when the race did. Every few minutes someone on a fixed-gear barreled across the finish line, not quite realizing that the race was over, and slammed into the growing number of stationary riders. Helmets, bike lights, and water bottles went flying. In the end, only one person was taken away in an ambulance. Most of the riders who had crashed along the course, including Vasquez, got back on their bikes and completed the race.

At 6:15 a.m., Ward announced Stade, an L.A. native, the overall winner. Which meant that the tags returned to the city. The riders dispersed within ten minutes, and Ward jumped in his car—which was about to be towed. By 6:30, there was little evidence the ride had ever occurred. No podium. No crowds, just a few policemen on motorcycles riding up and down Ocean Boulevard, clearing the remaining riders off the street.

But next year they’ll be back. If the trend holds, there will be thousands more of them. “Being responsible for 4,000 people weighs heavy on me,” Ward told me weeks later. “Every year I get more anxious. I keep thinking it’s the last one. But I get so many e-mails from people thanking me for the good times they’ve had, it’s hard to walk away.”

That’s the problem with underground races: they’re fun, so everyone wants to do them. Officer Helper told me that the ride is at capacity and won’t be able to get any bigger without a major sponsor and a permit. In the months following the race, Ward had been in talks with L.A. Marathon organizers. “I have my fingers crossed,” he told me.

And if it stays underground, future races might have a hard time attracting top-tier riders like Stade, Celso, and Miranda. USA Cycling has said that it will enforce the rule barring licensed riders from unsanctioned events beginning in 2014. The consequences for any rider ignoring the rule—which would include most of the lead pack at the 2013 Crash Race—would be a $105 fine and a one-month suspension. Without the top competitors, the event could find itself downgraded from the Crash Race to the Crash Ride.

As Ward continues to speak with city officials, police, and marathon organizers, he’s beginning to get a taste of how a sanctioned event might work. “I’m currently embroiled in paperwork and process. It’s frustrating as hell, especially when all you want to do is throw a kick-ass race, have a beer, and share war stories after,” he says. “I miss that already.”

Matt Skenazy is an assistant editor at Outside Magazine.

