“Fat bikes allow people to ride bicycles in places that previously were simply not possible,” says Peter Koski, product development engineer at Salsa.
Fatties have been around for more than a decade but have only captured the mainstream cycling world’s attention over the past couple of years because of their versatility and a rise in extreme adventure races. Geoff Harper recently rode his 9:Zero:7 Tusken over 500 miles of beaches on the southeastern shores of Iceland, and hundreds of competitors ride various fat bikes over the challenging Arrowhead 135 course every January in Minnesota.
So How Do They Work?
Standard mountain bikes typically have a wheel width of a little over 2 inches; fat bike tires can be double that or more. The massive tires can also be ridden at dramatically lower pressure. Manufacturers suggest most standard mountain bike tires be filled to 25–65 psi, but the massive fat tires can run 10 psi or even lower. The lower pressure allows more of the tire to grip the ground under the rider’s weight, drastically increasing the rubber’s surface area.
For conditions such as snow or sand, that extra width allows the rider to float more easily over the unstable terrain. Over snow-packed singletrack, riders can glide through icy corners that may have sent them hurtling to the ground on a standard mountain bike. The squishier tires can also make for a much more comfortable ride on the trail.
Fat bikes make it easier to ride in or over the snow, but that doesn’t necessarily make it effortless. You might stay more upright, but you still really need to muscle your way through snowdrifts or thick sand. You’re definitely going to get in a workout.
There is a weight penalty as well. The larger rims and tires typically add at least 4 pounds to the bicycle’s weight. The penalty isn’t too severe, though; most riders are more concerned about having fun than shaving ounces off their bikes.
Is This For You?
Basic fatties from Surly and other respectable manufacturers start around $1500, about the same as an entry-level full-suspension mountain bike.
Fat bikes are so much fun that some riders are selling their mountain rigs and riding their fat bikes year-round. While there are a few front- or full-suspension fat bikes on the market, most remain fully rigid. (Salsa says it’s working on a suspension prototype but doesn’t know when it will be ready to hit the market.) But while the fatties’ squishier tires offer the equivalent of about 2 inches of travel (most full-suspension bikes start at 4 inches of travel and go up to 10), that might not be enough for more difficult trails. The rig’s beefier girth also makes it more difficult to navigate technical single track.
So if you’re looking to continue riding far into the winter or do an Iditabike-style adventure race, the Mukluk or one of its fatty brethren is an ideal rig to add to your collection. But it’s probably not going to be completely taking the place of your mountain bike just yet.