It was a frozen day in 2006 when I first swung a leg over the frame of a fat bike. Back then these large-tire bikes were made only by custom frame-builders who liked to pedal in snow and a single Minnesota brand, Surly Bikes, which mass-produced the first notable bike in the “fat” genre with its Pugsley frame.

Wide rims, extra-large tires, and weirdly-dimensioned frames to make it all fit together define a fat bike, a cycling subcategory that’s garnered a serious following now in 2012.

Bike shops report selling out of fat-bike stock. Brand managers at Surly and Salsa Cycles, another fat-bike maker, have told me demand this year has overwhelmed supply.

What is the appeal? From improved traction on dirt to flotation when riding through snow, the obese tires let a bike roll where it has not rolled before.

The wide rubber — 4+ inches across, or twice as wide as most mountain-bike tire tread — adds notable grip on the ground, and the extra surface area does not allow the wheel to sink as much into soft surfaces like snow or sand.

Another distinction: You can ride with significantly lower tire pressure. Think 15 or 10 psi, or even lower still. This gives the tire some significant squish, and that play translates to more rubber conforming onto the trail for serious grip.

On snow, the wide tires have more surface area touching down and simply “float” a bit more rather than digging in like skinnier tires can. Finally, with all that squishy rubber under you, suspension is not necessary for most fat bikes.

Beyond Salsa and Surly, at least a half-dozen additional bike companies now sell frames or complete-build fatties. Chain Reactions Cycle, a bike shop based in Anchorage, Alaska, sells fat bikes branded 9:ZERO:7. Moots, a high-end builder in Colorado, sells its fat FrosTi model. Fatback is another Alaska brand.

Fat bikes cost roughly $1,500 to $5,000, depending on frame type and components. They are heavy (30 to 40 pounds on average) and slower than mountain bikes on regular terrain.

But in snow, on sand, or for some serious grip on dirt or rocky terrain, nothing else made compares to a fatty. Get on one this year if you can. You might never want to be skinny again.

–Stephen Regenold is founder and editor of Connect with Regenold at or on Twitter via @TheGearJunkie.