Fatbike

Fatbike being ridden over the snow

Sun Spider AT fat tire bicycle, featuring 26 x 4 inch tires, aluminum frame, and a 2-speed hub, is on display at the Carnegie Science Center in Pittsburgh, Pennsylvania.

Fatbike in Mexico

A fatbike, also called a fat bike or wide tire bike, is a bicycle with over-sized tires, typically 3.8 in (97 mm) or larger and rims 2.6 in (66 mm) or wider, designed for low ground pressure to allow riding on soft unstable terrain, such as snow and sand. Fatbikes are built around frames with wide forks and stays to accommodate the wide rims required to fit these tires. The wide tires can be used with inflation pressures as low as 5 psi (340 hPa) to allow for a smooth ride over rough obstacles. A rating of 8–10 psi (550–690 hPa) is suitable for the majority of riders.

Usage

Fatbikes were invented for winter trail riding and racing in sub-arctic Alaska on the Iditarod Trail and simultaneously, for touring the deserts of New Mexico. They are extremely versatile bikes, capable of traversing diverse terrain types including snow, sand, desert, bogs, mud, pavement, or traditional mountain biking trails. In several states, fatbike-dedicated groomed winter trails have been created.

History

Picture from series "Strange but True!", placed by Currys Ltd in the cycling press, before 1932

Although early versions of fat-tired bikes were probably built on a limited basis as long ago as the early 1900s, the original fatbike was ridden in 1986 across the Sahara using fat tire prototypes from Michelin. In the late 1980s, Alaskan frame builders began experimenting with custom components and configurations designed to achieve a large contact patch of tire on snow. Steve Baker, with Icycle Bicyles in Anchorage, was welding together two rims and even three rims and built several special frames and forks that could accommodate two or three tires together. Roger Cowles (riding his famous "6 Pack"), Mark Frise, Dan Bull and one other rider rode the entire length of the Iditarod Trail from Knik to Nome in 1989. Simultaneously, in New Mexico, Ray Molina had commissioned Remolino 3.1 in (79 mm) rims, 3.5 in (89 mm) tires, and frames to fit them. He wanted the bikes for his guided tour business in the soft sands of the Mexican and Southwest arroyos and dunes. Mark Gronewald, owner of Wildfire Designs Bicycles in Palmer, Alaska met Molina at the 1999 Interbike convention in Las Vegas and rode one of Molina's prototypes at demo days. In late 1999, Gronewald and another Alaskan frame builder, John Evingson, collaborated to design and build several bikes using Molina’s rims and tires. Gronewald and Evingson then began producing their own separate lines of fat-tired bikes in 2000. Rims and tires were imported to Alaska where Wildfire and Evingson began making small, handmade production runs and custom-ordered frames built around Remolino 80 mm rims and 3.5-inch tires. Gronewald coined the trademark "Fat Bike" in 2001 and used it as the model name for his bikes. Gronewald originally worked with Palmer Machinery for welding and later contracted frame building to Mike DeSalvo at DeSalvo Cyles of Ashland, Oregon. Gronewald continued to sell his original fatbikes until 2011. Gronewald's design featured an 18 mm offset wheel and frame built to allow full range gearing, since he was using standard hubs and bottom brackets available at the time.

Wildfire and Evingson bikes were used in the Iditarod Trail races beginning in 2000. Also that year, Mike Curiak from Colorado set a record on the Iditarod Trail in the IditaSport Extreme race to Nome on a modified Marin bike with Remolino rims and tires. Surly Bikes released the Pugsley frame, in 2005, and began producing Large Marge 65 mm rims and Endomorph 3.8-inch tires in 2006. The Pugsley frame, rim and tire offerings made fatbikes commercially available in local bike shops worldwide. The Pugsley bikes also featured the offset wheel and frame build.

Other early versions of the fatbike were normal mountain bikes equipped with SnowCat rims, created by Simon Rakower of All-Weather Sports in Fairbanks, Alaska in the early 1990s; or with multiple tires seated on two or three standard rims that had been welded or pinned together. Rakower was involved with technical support aspects of the Iditabike (later IditaSport) race, which started in 1987. Since 2002 the race continued on the same trail under the name Iditarod Trail Invitational (ITI). Rakower started hand making extra wide rims for participants by welding two rims together and cutting off the middle ridge known as the snowcat rims 44 mm. S. Rakower produced those rims from 1991 through 1999. Many riders on the Iditarod Trail used a Geax tire with the snow cat rim. Enthusiasts would cut and sew tire-carcasses together to maximize the size of the tire and utilize all the available space between the seat stays and chain stays; this tire and rim combination would maximize the bicycle's footprint, increasing flotation on winter trails. Soon after, Rakower decided to design a 44 mm rim from scratch and had it produced. SnowCats revolutionized winter cycling, as they could be fitted to nearly any commercially available mountain bike.

Mike Curiak from Colorado set a record on the Iditarod Trail in the 2000 race to Nome. Surly Bikes released the Pugsley frame in 2005 and began producing Large Marge 65 mm rims and Endomorph 3.8-inch tires in 2006. The Pugsley frame, rim, and tire offering made fatbikes commercially available in local bike shops worldwide.The Pugsley bikes also featured the offset wheel and frame build. Fatback Bikes came online in 2007 adding the carbon Corvus fatbike. Another Alaskan brand 9:zero:7 joined in 2010 also offering a carbon fatbike. Other bike manufacturers have also entered the fatbike market recently including Trek, with the Farley, Salsa with the Beargrease and Mukluk, and Specialized with the Fatboy and On=One with the Fatty. Others followed since 2014 Rocky Mountain, Felt, Kona, Pivot and many more. In December 2012 Eric Larsen (Polar Explorer) attempted to ride a fatbike to the South Pole. He made it a quarter of the way before he had to turn around. In 2013 and 2014 there were three cycling expeditions to the South Pole. Maria Leijerstam became the first to cycle to the South Pole, across the South Pole Traverse road. She rode a tricycle with fatbike tires. Juan Menéndez Granados skied and rode a fatbike to the South Pole. On 21 January 2014, Daniel P. Burton became the first person to ride a bike across Antarctica to the South Pole. Burton started at Hercules Inlet, and biked 775 mi (1,247 km) to the South Pole. He rode on a carbon fiber Borealis Yampa fatbike with 4.8 in (120 mm) wide tires. The Iditarod Trail Invitational (formerly known as Iditabike and Iditasport Extreme and Iditasport Impossible) race in Alaska has grown into an international event and is the holy grail of fat biking events, offering a 130-mile, 350-mile and 1000-mile distance. The event spurred the creation of many other winter ultra events in the United States, Canada and Europe that are accepted qualifiers to get into the Invitational.

Fatbike wheels and dimensions

• 26+: 26" rims, width >35mm, typically 50mm. Tire widths typically >2.5", e.g. 2.8", 3.0".
• 27,5+/650+: 27,5" rims, width >35mm, typically 50mm. Tire width typically >2.5", e.g. 2,7"-3,25".
• 29+: 29" rims, width >35mm. Tire width typically up to 3.0".
• XL: 26" rims, width 60mm-103mm. Tires widths typically >3.5", e.g. 3.8", 4,5", 4,8".
• 2XL: 26" rims, width 80-103mm. Tire width >5.0".

Events

As the popularity of fatbikes has expanded, fatbike specific events (races, race series, tours, and festivals) have emerged. Examples include the annual Global Fatbike Summit (since 2012), the Fatbike Birkie race which is part of the Great Lakes Fatbike Series (2014-2015 season: 8 races held across 3 states), the US Open Fatbike Beach Championships (inaugural, 2015), the USA Cycling Fat Bike National Championship (inaugural, 2015), and the 45Nrth Fatbike Triple Crown race series.

See also

• List of cycling topics
• Antarctica Cycling Expeditions