Motorcycle underwear is any type of garment worn close to the skin underneath motorcycle clothing. In many cases, motorcycle underwear is no different from any other type of underwear, but motorcycle racers often choose to wear underwear that is breathable, lightweight, comfortable, and durable. The underwear set may include a top and bottom, while just a simple pair of underwear may include bottoms only. The bottoms may be shorts or they may be full-length; tops are usually long sleeved, though some versions of the underwear can be short sleeved as well.
Motorcycle racers can work up a sweat when racing, and wearing motorcycle underwear can help keep the skin dry and comfortable during the race. When the skin becomes moist from sweat buildup, chafing is more likely to occur, especially on parts of the body that routinely move throughout the race. In cool conditions, sweat buildup on the skin can lead to difficulty staying warm, and in the warm weather, it can be uncomfortable. Motorcycle underwear helps to combat these problems; the underwear is breathable, so it wicks moisture away from the skin and allows air to pass through to the skin to keep it cool and dry.
Very often the motorcycle underwear resembles bicycle shorts or tights. The material may be Lycra®, spandex, polypropylene, or certain types of polyester, and the underwear is always tight-fitting to prevent the material from bunching up and causing discomfort. Unlike bicycle shorts, however, the motorcycle may or may not include a chamois pad for extra comfort in the seat of the shorts. The waist band of the shorts may also feature a drawstring to ensure the shorts or tights stay firmly in place, even when the rider is bending forward.
Motorcycle underwear tops are usually made from a lightweight synthetic material that is breathable, though unlike the shorts or tights, the tops may not necessarily be tight fitting. Some versions of the tops are tight fitting, and choosing between tight fitting shirts or loose fitting shirts boils down to a matter of preference.
The tops and bottoms of the underwear set may also be wind-resistant or windproof. A motorcycle rider is likely to reach high speeds while riding, so wind resistant materials can help keep the rider warm and comfortable during the rides. Windproof materials tend to be thicker than other styles of underwear, though they are still usually thin enough to fit underneath other clothing.