Like two other pretty damn prominent inventions, calculus and television, the fatbike was apparently dreamed up in two very different places for two very different reasons at about the same time. Simon Rakower started making excessively fat tires in Fairbanks, AK, for the snow-covered Iditabike race around the same time Ray Molina was chasing chubby rubber to better lead tours through the sandy New Mexico desert. Whichever version you believe, these events kicked off a big trend in mountain biking that’s quickly making its way in from the fringe.
The real catalyst for fat bike popularity was the widely distributed and decidedly off-kilter Surly Pugsley, introduced in 2005 with 3.8-inch wide tires — nearly double that of a traditional mountain bike — and a steel frame that was designed specifically around the new tire format. The advantage of such impressive girth is both unprecedented flotation on soft surfaces (for the same reasons a snowshoe works) and the ability to run the tires at incredibly low pressure (10-15 PSI compared to your mountain bike’s 35 and road bike’s 120) for better grip. Since 2005, loads of companies have introduced fat bikes in their lineups, spurring technical and design advances and bringing the fatties up to par with traditional mountain bikes. Case in point is the impressive Borealis Yampa XX1, a carbon-fibered, wide-tired beast that contains plenty more design features than meets the eye.