According to Massachusetts law (M.G.L. Chapter 90 Section 1), a "motorized bicycle" (also known as a “moped”) is defined as a pedal bicycle which has a helper motor, or a non-pedal bicycle which has a motor, and:
has a cylinder capacity of no more than 50 cubic centimeters;
has an automatic transmission;
is capable of a maximum speed of not more than 30 m.p.h.;
complies with all applicable Federal Motor Vehicle Safety Standards (M.G.L. c.90 § 1C).
Examples of such bicycles include styles of mopeds and dirt bikes.
Operators of motorized bicycles are subject to all Massachusetts traffic laws and regulations, as well as specific laws (M.G.L. c. 90 §1B-E) which mandate that the vehicle / its operator must:
Drive at speeds 25 mph or lower
Drive on appropriate surfaces which include bicycle lanes along roadway
Use the proper electronic and hand signals before stopping or turning.
Be at least 16 years of age and have a valid driver's license or learner's permit.
Wear approved safety helmets.
Be registered with the Massachusetts RMV (motorized bicycles are classified as "motor vehicles") and present a valid registration sticker on the vehicle
And must avoid:
Carrying passengers while operating on a permit
Driving on (a) state highways and/or limited access roadways where bicycles are prohibited and (b) off-street recreation paths
In cities such as New York, Philadelphia, and the District of Columbia, motorized bicycles are banned within city limits. Currently, the City of Boston is looking to enforce a similar ban under Mayor Menino's “Operation Kickstand”, which would limit where the vehicles are allowed within the city. In addition to this ban, “Operation Kickstand” allows for better and more stringent enforcement of the laws regarding motorized bicycles.