On Sunday, 41-year-old cyclist Chris Horner became the first American to win La Vuelta a Espana and the oldest man to ever win a Grand Tour.

But with apologies to the real cycling fans of the Internet, I’m going to make five assumptions about you, the Grantland reader who stumbled on this article. First, you’ve only ever heard of the Vuelta in passing, if at all, and ditto for Chris Horner. Second, you’re wondering why you should care. Third, you lack some basic facts. Fourth, the first word that comes to mind when you come across a cycling story is “doping.” Fifth, you’ve yet to encounter the poetic side of the sport.

I make all these assumptions because each one of them was true about me as recently as three years ago. Since then, I’ve been seduced by the Tour de France, started to bike on my own in a very amateur way, and decided this year to expand my viewing to the Vuelta. And man, am I glad I did, because Saturday’s climb up the Alto de L’Angliru, a steep mountain road in Asturias, was the single best bike race I’ve ever witnessed, a slice of foggy drama that had me enthralled.

But I’m getting ahead of myself. First, there are a few things you need to know.

What Is La Vuelta a Espana?

The three most esteemed races in the cycling world are called Grand Tours, because they involve more than 20 individual races (“stages”) held on consecutive days, with only one or two rest days thrown in to break up the grind. If a rider manages to finish each race, he has essentially toured an entire country. The most famous of these, of course, is the Tour de France. The other two are the Giro d’Italia (Tour of Italy) and La Vuelta a Espana (Tour of Spain). Only one American rider, Andy Hampsten in 1988, has won the Giro. Technically, now that Lance Armstrong’s Tour de France titles have been stripped, Greg LeMond is the only American winner of that race (he did it three times between ’86 and ’90). Before 2013, no American had ever won the Vuelta.

Who Is Chris Horner?

Horner has been a professional rider almost 20 years, starting in 1995 in the States before moving to Europe for the Francaise des Jeux team two years later. Since then, he’s been known as a strong climber and a mediocre time trialist, making him an obvious domestique — literally “servant,” responsible for support and drafting and anything else the big shots need — for riders with a chance to win a Grand Tour. He even served in that capacity for Lance Armstrong, albeit after Armstrong’s prime. In 2008, while leading a teammate to a victory in an American road race, he picked up a fallen rider from a different team and carried him (and his bike) to the finish line. It’s a weird bit of synchronicity for me that the fallen rider was Bill Demong, a Nordic combined Olympian who would go on to win America’s first ever gold medal at a Nordic event — the 10km large hill combined — at the 2010 Vancouver Games.

Lately, Horner has started to find his own success, winning the Tour of the Basque Country (Spain) in 2010 and the Tour of California in 2011. He finished ninth in the Tour de France in 2010, and 13th in 2012. But an injury kept him out of the first two Grand Tour races this year, which turned out to be the ultimate blessing in disguise when he came to the Vuelta with fresh legs. There, on August 23, he won the first Grand Tour stage of his life. He did it again on Stage 10 a week later, but lost his overall lead to Vincenzo Nibali, the great Italian rider and winner of this year’s Giro, the next day. Nibali held the lead through Stage 18, but he could never extend it beyond 50 seconds over Horner. When the mountain stages returned, Horner began to take time back, a little at a time. On Stage 18, a breakaway by Horner helped him gain 25 seconds on Nibali, reducing his overall deficit to an impossibly close three seconds. That slim lead evaporated the next day, when he beat Nibali by six seconds to retake the lead by three seconds.

That left just two stages. On Sunday, they’d take the final ride into Madrid, a race contested by sprinters where it was all but impossible to gain any meaningful time on an opponent. Saturday, though, was anything but a formality. Saturday brought the race to L’Angliru.

What Happened on L’Angliru?

The brutal 12.2-kilometer climb, which comes at the end of an 88-mile race filled with other not-quite-as-brutal-but-still-pretty-damn-brutal climbs, is La Vuelta’s ultimate test. It was first included in 1999 to give the race a staggering mountain climb to rival the Alpe d’Huez and Mont Ventoux climbs at the Tour de France. In the span of those 12.2 kilometers, riders have to ascend more than 1,200 meters at an average gradient of 10.2 percent, maxing out at an insane 23.5 percent near the finish. To give you an idea of what that’s like, I recently took what I considered to be a toughish ride that included a five-mile stretch on an incline that felt like … well, if not a mountain, then at least a very steep hill. When I entered the route into MapMyRide.com later, I found out that the maximum gradient — maximum, mind you — was 7 percent. If that’s not enough perspective, look at the race profile:

That last peak? Yeah, that’s it. I couldn’t begin to even imagine reaching the summit with fresh legs and a pack of bananas, but these guys were being asked to do it at the end of four hours of racing.

So, the scene. Trailing by three seconds, and having failed against Horner on most of the mountains, the situation looked impossible for Nibali. How would he tire a superior mountain rider and actually gain time? But the Italian had more in store than anyone could have imagined, and as they began the ascent up L’Angliru, he actually attacked Horner, riding away from him on several occasions and daring him to follow. The higher they rode, the more he attacked, and a misty fog settled around them in the half-light. It was nature lending an aspect of mystery to what had previously been pure labor. Fans swarmed, camera motorcycles stalled, cars became stuck, and still the two riders staged their epic duel.

This video captures the critical moments, and because I know watching nine minutes of cycling is a lot to ask, I’ll give you the highlights below.

0:00 — With less than four kilometers left to race, Nibali makes yet another attack up the mountain, trying to leave Horner in his wake. “He’s just got to find three seconds here!” says Carlton Kirby, announcing on EuroSport with Sean Kelly. “And Nibali just can’t shake him!”

1:09 — “And Nibali goes once more in the cloud!” We knew Nibali races well in the rain, but this was the first time when it seemed like he might actually be able to gain some time, as Horner struggles to catch up. For Nibali, it was already a heroic performance, but now it felt like it might be more.

2:41 — They enter the toughest part of the climb as the gradient increases to 22 percent. The fans ignore the paltry Spanish police presence and the roadside barriers to crowd the roadway, shouting encouragement and mugging for the camera.

3:10 — Chaos. Fans and fog are blocking the view from the camera. Finally we get a glimpse of Horner and Nibali, locked on each other’s wheels, but they quickly disappear.

4:10 — The motorcycle camera, the only useful angle considering the fog, gets stuck behind a team car. Then it stalls out due to the steepness of the hill. The bikers leave.

4:49 — This starts a period of invisibility. We have no idea what’s happening with Horner and Nibali due to the motorcycle failure. We focus on Kenny Elissonde, a French rider making a grueling ascent in the lead.

5:43 — The fog thickens, and there’s no sign of Horner or Nibali. This is the first sporting event I’ve ever watched where we’ve actually lost sight of the main players. Watching it live, it created an unbearable sense of drama and anticipation. A second motorcycle was put into use, but it quickly got stuck behind a team car.

6:05 — Finally, the second motorcycle manages to get by the car. The camera navigates through the fog, and we’re waiting to see when it will find Horner and Nibali. It takes 30 seconds swerving around the mountain pass, but, then, out of the fog: There they are. And they’re together. And Horner’s in front.

7:00 — Starting here, the camera pulls alongside the pair and gets one of the neatest camera shots I’ve ever seen, a profile of two men in extreme pain. Horner out of his saddle, a mirthless rictus on his face, and Nibali behind, on his seat, shoulders rocking, struggling to finish the last two kilometers and gain those three precious seconds. Around them, a cacophony of beeping and shouting.

7:55 — Horner, after surviving each Nibali attack, makes one of his own, brilliantly speeding by a trio of faltering riders on the left. By the time Nibali can react, Horner is gone. The Italian trudges on, his tank on empty, and Horner disappears into the fog.

9:06 — “And running away right now is that man Horner, and look at him go!” It was at this point that I stood up from my couch and cheered, and received the look from my wife that you’d expect to receive when you get caught cheering for a cyclist.

The rest was history — Horner was gone, Nibali cracked, and the 41-year-old would lead by an insurmountable 37 seconds heading into Madrid. (You can see the last five minutes of the race here.) The ride up the fog had earned him every accolade — first American to win the Vuelta, oldest Grand Tour winner ever, and a much-needed cycling hero for a country whose last icon has fallen into disgrace.

But, But, But … Was He Doping?

The curse of modern cycling is that no matter how many unbeatable tests are developed, or how much noise the governing bodies make about the clean new world, we’ll always wonder. And when a 41-year-old wins a Grand Tour event without ever having led one in his career, we’ll wonder a little more.

But for the optimistic take, I turned to my friend Tim Cupery, a longtime cyclist and cycling fan who knows far more about the sport than I ever will. He’s a Horner fan, but he makes a strong case for why he’s clean.

The main reason to suspect Horner of doping is the Grand Tour–winning performance at his age. But I think it’s plausible that he could have won this clean (assuming the other top guys he’s competing against are clean as well). Here are the reasons:

1. Very few riders target the Vuelta as the main goal of their season. Other top riders on GC [general classification] had ridden either the Giro or the Tour. By comparison, because of his knee injury and surgery, Horner was very fresh coming into the Vuelta. This may be even more important for a rider of his age. He was able to race well at Utah (in the U.S.) and time his peak for the Vuelta.

2. The course was perfect for him. Horner has always been a great climber, and is somewhere between OK and good at time trials. With 11 summit finishes and one time trial (which was shorter and somewhat hilly), the route played to his strengths.

3. Horner is clearly a very talented cyclist, but has had few opportunities as team leader for a Grand Tour. He dominated the U.S. pro circuit in the early 2000s, and his initial Grand Tour opportunities on the European circuit did not afford him team-leader status. He finished ninth in the 2010 Tour (where he initially started out as a support rider). In 2011, he was a coleader going into the Tour, but crashed out with a bad concussion.

4. Over the past few years, Horner has watched his diet and weight more carefully than earlier in his career. He is known for his love of burgers and junk food, and has gotten more disciplined (and lost weight). This is key for climbing performance, as the most important metric is power-to-weight ratio.

And there you have it. How you view Horner on the doping issue is a matter of belief, and if you doubt him, well, cycling probably deserves that. But for a few hours on Saturday, in the fog of the Spanish mountains near Asturias, I found it impossible to be cynical.