It's a Friday evening in late November, and the air at Grumpy's Bar & Grill in Minneapolis is abuzz with the electricity of weekend release. Friends backslap and crowd six to a booth. Coats and bags and bike helmets pile up on the floor.

"Take note of the puke bucket," someone yells as I elbow through the crowd, stepping over cords and onto a little stage. It's my turn to pedal the stationary bike hooked up to the computer. I have 20 seconds to sprint and spin along an imaginary 500-meter course.

"GO TIGER!" the screen flashes. And thus I start my ride.

This is goldsprint racing, a rising offseason cycling activity that melds a stationary bike trainer with a video game. Riders pedal to move wheels on a computer-connected roller system, transferring power output to its virtual equivalent onscreen, where an animated biker ticks along.

Faces go beet-red in seconds, nostrils flare and rubber literally burns as riders start up and spin full-bore on aluminum rollers. Each 20-second session provides a great physical test for the rider as well as an entertaining spectacle for bar patrons in the crowd. The barf bucket stands ready for both causes.

"Come on, come on!" the emcee screams. I'm halfway through my session, an elimination round where riders go solo to prove their worth. My head is down, body leaning out over handlebars. I'm gasping, heart racing, the room fading in and out, bursts of light and audible flashes.

"Five seconds to go," someone shouts.

Goldsprints -- which were popularized in cities such as New York and London in recent years but are new to Minneapolis -- have a historical connection to roller racing, a similarly obscure format that's been around for decades. Roller racing employs a mechanical system to move clock arms on a large dial face. Each revolution of the roller under a rider's wheel transfers to gears that measure and pace off speed and distance traveled.

For goldsprints, computer code and magnetized sensors are used in lieu of gears and clock dials. At the Nov. 30 Grumpy's event -- first in a series of four "ColdSprints" to be held at the bar this winter -- a plasma screen over the stage revealed riders' distance traveled and virtual speed in mile-per-hour readouts.

None of the equipment for goldsprints is available commercially. The Grumpy's setup was assembled ad hoc by volunteers from the local bike community and Little Guy Racing, an area cycling team. Two local bike shops, Behind Bars Bicycle Shop and One on One Bicycle Studio, donated the rollers and other cycling equipment. Racers paid $5 to ride, with proceeds donated to a local food shelf.

Behind the scenes, Landon Bouma, a 30-year-old computer programmer from Minneapolis, spent two months creating a custom program for the ColdSprints series he calls "Dash, Minneapolis!" An IBM laptop, a cannibalized bike computer, a magnet sensor, some lead solder and a networking port to connect the analog rollers to the digital interface rounded out Bouma and crew's Frankenstein-ish creation. "It was a ton of work," Bouma said.

Race night last month drew about 65 riders and more than 150 spectators. The action started at 7 p.m. with Bouma manning a laptop up front while Tim Hayes of Little Guy Racing served as emcee. "Let's give it up for Jake!" Hayes shouted, signaling Jake Helmbrecht, one of his teammates, to come forward and ride.

Helmbrecht straddled the stationary bike. He spun a couple revolutions to warm up. Then the screen flashed: "R U READY?"

"Go!" screamed Hayes.

Helmbrecht gritted his teeth, leaning far forward to put force on the pedals. He spun into a blurring cadence, grunting, breathing, wheezing as his animated vestige blipped onscreen along the course.

The crowd alternatively watched Helmbrecht and the clock, cheering, hoisting beers, straining to see, then counting down in unison at the end: "Five, four, three, two, one!"

In 20 seconds, Helmbrecht had traveled a virtual 1,318 feet, averaging speeds above 40 miles per hour, enough to put him in first place for round one -- a position he held for the rest of the night.

My effort yielded a 1,200-foot distance in the first round's allotted 20 seconds, a middle-of-the-pack score. Physically, the goldsprint format was unlike anything I'd ever done, as you're forced to go from a resting heart rate immediately to your max physiological output.

For 15 seconds, my legs and lungs held out. Then things got weird, the room going quiet, lights flashing. I was on the verge of blackout. I fizzled through the final 2 seconds, then leaped off, pushing into the crowd lightheaded and woozy to clapping, backslapping and cheers.

Hayes grabbed the microphone. "You got it, nice work," he shouted. "Now who's up next?"

Stephen Regenold is a Twin Cities writer and author of the syndicated column