While no single, universal "Congress definition" exists, federal law (NHTSA) defines a motorcycle as a motor vehicle with power, a rider's saddle/seat, and not more than three wheels, while recent Congressional bills (like H.R.3385) propose updating this to specify handlebars, astride seating, specific controls (handlebar/foot), and capability over 30 mph, moving away from some three-wheeled car-like vehicles being classed as motorcycles.
Key Federal (NHTSA) Definition (49 CFR § 571.3)
- A motor vehicle with motive power.
- Has a seat or saddle for the rider.
- Designed to travel on not more than three wheels in contact with the ground.