– Riding a fat bike this winter for the first time stoked a flicker of interest in me.

Doing my first Fat Bike Birkie race sparked a gas fire.

Last Saturday in northern Wisconsin, over parts of the same woodland trails favored each winter by thousands of skiers, fat bikers had their shot. More than 800 registered riders rolled out over two distances (47 or 20 kilometers), claiming their part in the largest winter fat bike race.

Opting for the short, I had decided on a slow-and-steady approach. Yeah, right. The Birkie trail had its own plan.

Like hanging onto the tail of a living thing, I was pulled down whip-fast descents only to furiously climb up the other sides. My emotions swung this way and that, too. There were brief, transcendent moments to take in winter’s beauty as sunlight sprayed through the pine and birch. Then, the reality of my ride shoved aside those thoughts. I would need more mental agility than physical.

Riders came up alongside, and riders dropped back. Riders — I among them — crashed, too. Carved-up, loose snow (“mashed potatoes” in trail vernacular) was at times a challenge for even my 4-inch-wide tires made for such terrain.

No matter. We were at the epicenter of something that’s new and evolving — and wildly fun.

“It’s interesting to anticipate what will happen with the sport,” said Allan Serrano, the Birkie race director.

Serrano said a pack of elite racers or races don’t exist because of the relative newness of the sport. It’s more of an “experience crowd,” but one that appears fit and knowledgeable enough to take it up a notch.

“It remains to be seen if we get that type of crowd, and we can support that type of expansion,” Serrano said.

The riders — in the short race at least — ran the gamut. Some were dressed as if they’d just dropped in from “Outside” magazine, with handlebar mitts and biking boots laced just so. But there was the middle-aged guy in jeans, or the racer in an old sweatshirt and athletic shoes, who got after it, too.

The rides also were eclectic. It was a bonanza of Salsa, Surly, Framed, Borealis, 9:ZERO:7, Trek and Motobecane, among others. Some made of steel, some aluminum with carbon forks. Or some all carbon, like the Framed ­Alaskan rocket that carried me.

As at any citizen race, that twitchy energy of anticipation in the hours before the Birkie hung in the air and in my stomach. But, too, there was a new-sport vibe to this event that was youthful, upbeat and nonjudgmental. For sure, people were out to ­compete. Many, too, were out for a good time. They got both.