A Dual-pupose motorcycle can best be described as a motorcycle which can handle two types of terrain or situations with almost equal ability. Popular dual-sport models include the BMW GS series, KTM Adventure series, Kawasaki KLR and KE, Suzuki DRZ and V-Strom, Honda Trans-Alp, Yamaha XT & TW and many more.
A dual-sport Motorcycle compromises the light weight and off-road capabilites of the typical dirt bike in order to offer a safer, more comfortable ride on the road and comply with regulations that affect street motor vehicles. Thus Dual-sports have all necessary components for street homologation such as turn-signals, speedometers, mirrors, as well as safety, comfort and convenience components which may include anti-lock braking systems, luggage, more comfortable seats, auxiliary lighting, and other optional items.
A dual-sport is often conceptualized as a street-evolved dirt machine, although recently several manufacturers (for example Buell with the Ulysses XB12X and Ducati with the Multistrada) have followed an opposite trend, especially manufacturers who usually didn't compete in the dirt-bike market. The offroad heritage of these bikes is reflected most prominently in its suspension, which offers more travel than a street bike. Other featuers common to off-road bikes, such as Handguards and wheel covers (mudcovers) usually appear in these models.
The tires fitted in dual-sports are also a compromise, offering deeper treads than a street bike, while laking the knobbed surface of dirt tires. This compromise offers a fairly good road performance as well as superior dirt handling over normal road tires.
Other types of Dual-Sports
When a dual-sport bike is kitted out for long distance travel, with accessories such as oversized tanks, luggage compartments, and other distance-oriented gear they are often referred to as "adventure" bikes, offering limited touring capabilities, superior to that of the average motorbike, but less than a full fledged tourer such as the Honda Goldwing series.
Enduro motorcycles can also be dual-sports, if they are street legal. These motorbikes are generally speaking between the average dual-sport and a true off-road motorcycle.
A supermoto (also known as a supermotard or motard) is a converted enduro with a stiffer suspension, smaller front wheel, road tires and an oversized front brake designed to be primarily run on asphalt. When made street legal, these bikes may also be considered to be a type of dual sport. In this case, these motorbikes could be seen as somewhere between a full on-road motorbike and a "true" dual-sport.