A fat cycle (also called fat cycle or fat-tire cycle) is an off-road bicycle with oversized tires, typically 3 inches (77 mm) or larger and rims 2.16 inches (55 mm) or wider, designed for low ground pressure to allow riding on soft, unstable terrain, such as sand, bogs and mud. The wide tyres provide you with extra grip and traction and combined with low tyre pressure, you’ll find that you’re able to pedal over terrain that'd make conventional tyres sink.