Dirt bikes are lightweight motorcycles designed for rough terrain and often used in a racing sport called motorcross. The three leading dirt bike manufacturers are all Japanese firms—Honda, Yamaha and Kawasaki. The market size is based on unit sales in the years listed.

Geographic reference: United States
Year: 2008 and 2009
Market size: 146,801 and 92,957 bikes respectively
Source: Dealernews, June 2009, page 34