Frank's North Star Tavern owner Frank Dorsey, disguised as Jason Voorhees competes in a roller cycling race at Franks North Star Tavern, 508 Locus Street, on Friday, Sept. 13, 2013 while Michele Berendsen holds his machete while cheering him on.

Michele Berendson, right, shouts words of encouragement to Sybil Gibbs, both of Lawrence, while Gibbs competes in a roller cycling race at Franks North Star Tavern, 508 Locus Street, on Friday, Sept. 13, 2013.

Michelle Kogl, Lawrence, raises her arms as she's introduced to the crowd before competing in a roller cycling race at Franks North Star Tavern, 508 Locus Street, on Friday, Sept. 13, 2013.

Exterior of Frank's North Star Tavern, 508 Locus Street.

Something that sets Frank’s North Star Tavern apart from bars found on the opposite side of the Kansas River is the more “mature” crowd, said owner Frank Dorsey.

But if you were to step foot inside this North Lawrence dive bar on Friday the 13th, you would have seen people of all ages waiting to compete in its second “Indoor Roller Races” while sporting attire from sombreros and reflector vests, to kilts and various animal costumes, and, of course, a woman carrying a miniature E.T.

It’s exactly how it sounds. Two bikes attached to rollers to remain stationary, hooked up to a computer to track the 300-meter race and the speed of the two competitors. All of this in the middle of a rowdy crowd guzzling 8-Bit beer infused with fruit, the special that came with the $10 entry fee for three races (proceeds went to the Ballard Center). And just in case of too much, ahem, excitement, there was a bucket in between the two bicycles.

“If you do this while drinking, one of the side effects may be vomiting,” said Aaron Apel, emcee of the event and owner of Big Poppi Bicycle Company. “It’s only happened once, but we do have this really neat bucket here labeled ‘spew.'”

Dorsey admits this sort of thing wasn’t in mind when he opened the bar at 508 Locust St. with his wife, Sarah Mathews, in May of last year. But he was looking for a different vibe than Mass. Street bars.

“It’s the kind of place where basically I’m my own target demographic,” Dorsey said. “I worked on Massachusetts for a long time. I got married, and I have a child now. I don’t want to necessarily be out that late. I just want a comfortable place to hang out that is not really that loud and obnoxious.”

He’s had his fair share of diverse bartending experiences. While he has worked at Tellers, Rick’s, and The Bourgeois Pig, Dorsey also bartended in New York City and Cambridge, England. One of his most colorful customers was a one-eyed hash dealer who used to be a Hell’s Angel in what he calls the “dodgiest part of Cambridge.”

“He would take his eyeball out and put it in his pint of cider to keep people from drinking it,” Dorsey recalls.

As offbeat as indoor bike race event may sound, more and more bike (and bar) enthusiasts charged into Frank’s as the competition started close to 9:45 p.m., resulting in around 20 competitors and a large cheerleading section inside the bar and out front. It looks like a simple race, but most hopped off the bike and waddled away to grab a drink and wait for their legs to function again.

“I did it last time and I was sore for days afterwards,” said owner Dorsey.

Dressed like a serial killer and equipped with a real machete, Dorsey had the second-best time of 15.73 seconds for the first round of the night, making a name for himself as not just an entrepreneur but also a bike racer.

Dorsey’s open to any event that sounds fun and will bring in a unique, niche crowd. There are regular shows (from metal to blue grass/country) on Friday and Saturdays, karaoke every Wednesday at 9 p.m., comedy and improv performances, “Breaking Bad” watch parties, and DJs in the basement. Keep up with the somewhat random events on the Facebook page, starting this Saturday with the “An Excuse to Hang Out at Frank’s and Talk about Motorcycles” event at 3 p.m.

Once again, it’s exactly how it sounds.