Matt Stile was nervous about his first underwear ride, but also excited.

"I found it online," he said. "I was looking for my first ride with a group of people."

It just so happened that ride was clothing optional. And Stile got into the spirit with some bright emoji-printed boxer briefs.

The monthly Pittsburgh Underwear Bike Ride runs from May to October as a way to promote positive body image and bicycle safety. It has grown from its humble beginning in 2012, when about 30 participants took part in the initial ride. But on a stormy September night, the turnout was small.

Organizer Scott Kowalski addressed the group of about two dozen bicyclists in Lawrenceville, opting to omit a planned stop in the route and instead focus on their end destination: the Wheel Mill bar where drinks and music were waiting.

The general aura at the event was simply having fun. Some got fully into the spirit with silly underwear, while others were there mainly for the companionship of other bicyclists.

Nia Ingram, who lives near Carlisle, came out to Pittsburgh to see her friend Eric Schreibeis. The two had spent a couple days biking around the area and were topping off the visit with the underwear ride.

"It's fun, you ride down the street and, when the weather's nice, all the restaurants have the fronts open," Schreibeis said. "Everyone's looking out and yelling and having a good time."

He has participated in several underwear rides before, but this was Ingram's second of the sort. Still, she touted the vibe as a reason to participate.

"The atmosphere is freaking awesome going everywhere," Ingram added. "Everybody's like 'Whoop Whoop!' and yelling, honking."

The final underwear ride of the year is the Halloween ride. Costumes are encouraged but not required.