Michael Carl, mid-spin. (Photo by Justin Bishop for Vanity Fair.)

Why would anyone opt to gather in a sweaty room on 21st Street between 5th and 6th avenues on a Thursday night while people were lined up on the sidewalk to get in to the plethora of neighboring bars?

Why, to attend Vanity Fair fashion market director Michael Carl’s Fleetwood Mac-themed spin cycle class, of course!

Last night, close to 40 fashion and PR industry types gathered at Flywheel Sports, the popular spinning gym and notorious SoulCycle rival, to pedal furiously while an instructor in a cut-off shirt at the front of the room yelled at them not to use their towel — “Sweat is sexy!” — in a harshly Brooklyn-twanged accent.

If you are wondering how a seventies band like Fleetwood Mac could possibly have been sucked into this sweaty spin class, you’re not alone. “I’m obsessed with Fleetwood Mac,” said Mr. Carl, by way of an explanation. “It’s all I listen to, it’s all I care about.”

We told him we just weren’t sold on the idea of spinning to "Dreams" or "Go Your Own Way."

“Oh, I think you’d be surprised with Fleetwood Mac. A little 'Rhiannon'? Gets things going.”

This was not the first time Mr. Carl, professed fitness fanatic, hosted a workout session for people in the industry. He told The Observer he did a similar class that was Bon Jovi themed last year, and that he has been known to teach boot camp classes for the editors during international fashion weeks in Milan and in Paris, where the editors abroad can be seen working their abs in Italian parks and the Jardin des Tuileries.

“I do it to keep us all in shape cause all we’re eating during fashion week eat is pasta and French food,” he explained.

So how did this perfect Thursday night marriage of fitness-obsessed fashionistas and a Chelsea-based cycling gym come to be? When Mr. Carl wrote a recent article for Vanity Fair about getting into the spirit of the Olympics through fitness, he cited Flywheel as a favorite. The cycling gym seized the opportunity to capitalize on the endorsement, and invited Mr. Carl to bring all his friends.

The invite went out to the people Mr. Carl works with, and as a result many of the attendees seemed to know each other, or at least know of each other. We ran into a friend who works at a luxury fashion brand. “I’ve e-mailed half of these people for work,” she explained. “I’ve just never met them.”

For a man whose Twitter feed is as catty as it is amusing (One tweet from August 8: "yesterday I saw a girl wearing a denim romper and feather earrings, I took a picture, but then i felt bad about sending it, but it was awful”), he sure is friendly. As we headed to our spot, in a room of many size-zero girls and very few men—a pretty accurate representation of fashion industry employees in general—Mr. Carl called to us from his spot in the front row, “Do you need help setting up your bike?”

Mr. Carl had told us before the class that many of the guests present were first timers. “My advice for first time spinners is to have fun, don’t push it too hard,” he said. "And make sure to stretch!” He neglected to mention how complicated it would be to set up the stationary piece of machinery, and we watched as the room of fashion associates wrestled with their bicycles and with snapping their special Flywheel shoes into the pedals.

By the end of the hour we still liked spinning and we still liked Fleetwood Mac, but we definitely didn’t like them together. Still, we did learn one important lesson from the evening: relaxed hippie playlist or not, if you want some motivation for a good work out, exercise with 40 people in the fashion industry. Nobody is over a size six, and if that won’t get you pedaling your heart out, even if you’re listening to a slow-paced song like "Landslide," nothing will.