This was the biggest night of Peloton Homecoming, the annual convention for the bike’s most ardent fans, and it was presided over by Arzon and her merry band of hard-bodied fitness instructors. The next day, attendees would stand in long lines, braving the pouring rain to shake hands and snap photos with their Pelo-crushes. Some of the faithful had made the pilgrimage that weekend to take their 100th or 500th class in person instead of in their basement or guest bedroom; many were there to see friends they’d made in one of the innumerable Peloton-centric Facebook groups and Instagram communities for, to name just a few: Christians who spin, theater nerds who spin, moms who are lawyers (who also spin). All around me, people who knew one another only from the internet would spot a familiar face, explode into squeals, and scurry in for a hug. The evening was themed as a homecoming dance, but it was more like a bizarro high-school reunion.

Among the tonally disparate delights on offer were an announcement of new app features, a slideshow of Pelo-fans who’ve found love on the bike, and a concert from the ’90s alt-rock prince Beck. (Yes, Beck.) One of the company’s yoga teachers attempted to lead a mass meditation, which was mostly thwarted by the effects of the venue’s multiple open bars. The crowd was much more rapt when CEO John Foley stepped onto the stage—a particularly enthusiastic cheer went up when he unveiled controls that allow riders to independently adjust the volume of the instructor’s voice and the background jam.

The scene was the stuff of start-up founders’ wildest fantasies. By combining this rabid customer loyalty with a framework for putting professional instruction and equipment into private homes, Peloton believes it can be the exercise brand to rule them all. Which is not to say that investors are entirely convinced. The life cycles of American fitness trends tend to be short and brutal—Jazzercise or Tae Bo, anyone? When the company went public at the end of September, its stock price dropped 11 percent the first day.

Once upon a time, people went outside. Even after the Industrial Revolution moved labor indoors, people still took to the outdoors to play. Children were sent out of the house in the summer and told not to come back until dinner. Communities were oriented around block parties and municipal pools. Cities built grand parks. Kids walked to school.

Over the past half century, people started to stay in, move less, and get bigger (air-conditioning, cable, and then WiFi accelerated the trend). Work changed, too: More than 80 percent of American jobs are now predominantly sedentary, a near doubling since 1950. In the space of two generations, physical activity was recast as an organized, expensive, time-consuming pursuit of excellence instead of a routine part of daily life. Kids joined competitive sports leagues, and adults went to private gyms or bought equipment to mimic the activities they once did outside, such as biking. People who couldn’t afford these luxuries went without, and the disparity in health outcomes between the rich and the poor grew wider.