Every race needs a signature moment: At the Big Sur International Marathon, it's the breathtaking view from Bixby Bridge; in Boston, it's merciless Heartbreak Hill; at the Marathon du Medoc in Bordeaux, it's a midway stop at the famous Château Lafite Rothschild. At the inaugural Rock 'n' Roll Dublin Half Marathon, the payoff came after the race, when the beer began flowing like the River Liffey.

The race started as most runs do: Lanky racers in singlets and too-short shorts slurped back pre-race GU and stretched. What was notable was the size and provenance of the crowd. Some 6,500 people from 52 countries waited for the crack of the starting gun along the southern border of lush St. Stephen's Green. The corrals were packed tight and stretched along the entire southern border of the 22-acre park. Strange as it might seem to veteran racers, the size of the crowd was small for a Rock 'n' Roll, which seems to perfectly represent the mainstreaming of endurance sports.

Just as Ironman became the face of hard-core endurance racing and Tough Mudder assumed obstacle course-icon status, the Rock 'n' Roll Marathon Series – with a total of 25 races in the United States and another five in Europe – looks to be making a play for the top spot in running. Among the races stateside are Las Vegas, one of the largest marathons in the country, and a handful of the best-attended half marathons, including Nashville and San Antonio. San Diego-based Competitor Group, which owns the Rock 'n' Roll series, also owns a series of short-course triathlons called TriRock, one of the less intimidating mud runs, Muddy Buddy, as well as magazines and websites for running, cycling, and triathlon.

Shorter, more approachable races are the group's sweet spot. Though 13.1 miles may not be the sexiest distance to sell – "half" does sound pejorative – it is the most popular distance for American runners: Roughly 1.85 million people finished half marathons in 2012 compared to the 487,000 people who finished a marathon. And we can expect to see more races of shorter distance in the future.

"The 5k and 10k side have exploded, catching up to the growth rate of the half marathon," says Scott Dickey, CEO of Competitor Group. "The categories are really starting to show influence in the world of sports marketing. It's all based on health and wellness and living an active lifestyle."

Competitor Group emphasized this point in August 2013, announcing that it would discontinue paying appearance fees for elite athletes at domestic races, fees that historically range from $5,000 to $75,000, depending on the stature of the athlete. But if the decision to focus on the weekend warrior sounds benign enough, it's not without detractors. While Competitor Group will continue to reimburse travel expenses for athletes and pay prize money, members of the running community criticized the decision for undermining competition in the sport.

That may be, but if the growth of fun runs and obstacle course races is any indication, the key to popularizing endurance events is allowing people to participate and finish, rather than compete and lose. The way Competitor Group sees it – and what they're banking on in expanding the roster of international races – the athletes from 52 countries and 30 American states who went to Dublin were mostly there to have a good time and hear some music. By that estimation, finishing in five hours is less cause for embarrassment than a sign you got your money's worth.

After the Dublin race was over, competitors headed to the Temple Bar neighborhood for post-race nourishment. The preponderance of bright green finisher jerseys milling around all afternoon and evening made it abundantly clear that people had come as much for a pint of Guinness as a finisher medal. That's a race we'll lace up for.

More Information: Rock 'n' Roll's 2013 Brooklyn 10k takes place on October 12 in Prospect Park. The Cleveland Half Marathon is scheduled for October 6. Registration for most events costs less than $100.