A fat bike is a type of bicycle that is designed to ride on soft or unstable surfaces such as sand, snow, mud, and rocks. The defining feature of a fat bike is its wide tires, which can range from 3.8 to 5 inches in width or even more, and are typically run at lower pressures than traditional bike tires.
The wider tires provide increased surface area and traction, allowing the bike to float over soft or loose terrain rather than sinking in. This makes it possible to ride in areas where a regular bike would not be able to go. The wider tires also absorb shocks and bumps better than regular tires, providing a more comfortable ride.
Fat bikes were originally developed for use in snowy conditions, such as winter cycling or snow biking. However, they have become popular for other types of terrain as well, such as sand or mud. They are also popular for bikepacking and touring, as the wide tires can carry heavier loads over rough terrain.
The wider tires and increased weight of a fat bike can make it more challenging to ride on paved or hard-packed surfaces, and it may not be as fast or efficient as a traditional bike in those conditions. However, fat bikes are versatile and can be ridden on a wide range of terrain, making them a great choice for adventurous cyclists who want to explore off-road or unconventional routes.