The motorcycle terminology presented herein addresses two-wheel single track vehicles, as well as motorized three wheel cycles. Although two-wheeled, single track scooters and mopeds are similar to traditional motorcycles, they have many characteristics which differentiate them from motorcycles, and while some terms will apply, this Terminology addresses motorcycles specifically, unless otherwise noted. Likewise, some three wheel cycles may have some similar design features and share components with motorcycle, the dynamics and handling of three wheel vehicles differs from two wheel, single track motorcycles.

The terminology presents definitions covering the following subjects: dynamics and handling of single track vehicles, motorcycle categories and types, motorcycle crash dynamics and technology, and in-depth crash investigations, motorcycle design and components, systems, and equipment, motorcycle operation, operational environments and hazards, rider protective equipment including helmets and clothing, rider behaviors, motorcycle safety, competitive motorcycle events and the specialized motorcycles used those events, key national motorcycle-related organization, selected phrases commonly used uniquely by motorcyclists, and related performance measures and selected test criteria.

NOTE: Motorcycle emission terminology does not vary from automobile emission terminology and is not unique and therefore not included in this report.