Scooters and mopeds
Motorscooters are similar to motorcycles and are also designed for being ridden on the road. Scooters usually have the engine as part of the swingarm, i.e. their engines travel up and down with the suspension. They often have smaller wheels (generally less than 14 inch (357 mm) diameter), automatic transmissions, small (generally less than 125 cc) engines, and a step-through configuration allowing the rider to ride with both feet on a running-board and knees together.
In Mediterranean Europe, particularly Italy, scooters are very popular. In the United States, scooters have long been a fixture on college campuses and strapped to the back of Recreational Vehicles due to their portability and exceptional fuel economy. However much larger scooters with engine displacements greater than 250 cc are becoming more popular. The Honda Silver Wing, Honda Reflex, Yamaha Majesty, and Suzuki Burgman are the most popular "maxi-scooter" models available in the United States. Australia introduced the Honda Silver Wing 650 cc in late November 2006. The Italian-made, three-wheeled Piaggio MP3 also falls into the maxi-scooter category.
An underbone is a small-displacement motorcycle with a step-through frame, such as the Honda C70. They are differentiated from scooters by their larger wheels and their use of footpegs instead of a floorboard. They often feature a gear shifter with an automatic clutch.
The moped used to be a hybrid of the bicycle and the motorcycle, equipped with a small engine (usually a small two-stroke engine up to 50 cc, but occasionally an electric motor) and a bicycle drivetrain, and motive power can be supplied by the engine, the rider, or both.
In many localities, mopeds are subject to less stringent licensing than bikes with larger engines and are popular as very cheap motorbikes, with the pedals seeing next to no use. Mopeds were very popular in the United States during the late 1970s and early 1980s, but their popularity has fallen off sharply since the mid 1980s.