Chapter 3. Can My Vehicle Be Registered? Bicycle Conversion to Motorized Bicycle (Moped) If the bicycle has: * two or three wheels * automatic transmission * cylinder capacity of not more than 50 cc * maximum speed of 30 mph or less It must be registered as a Motorized Bicycle (moped). If the modified bicycle does not meet all of the above requirements, the RMV will not register it (as a moped, a motorcycle or a " limited-use vehicle " ) and it cannot legally be operated on a public way which the motor is being operated. Low Speed Electric Bicycle If all of the following apply, a bicycle will be deemed a " low-speed electric bicycle " under Federal law (15 U.S.C. s. 2085) and will not have to be registered with the RMV: * has two or three wheels * has fully operable pedals * has an electric motor of less than 750 watts (one horsepower) * has a maximum speed of less than 20 mph on a paved level surface, when powered solely by the motor Once a bicycle has been converted to a Motorized Bicycle it is now subject to a sticker registration. Click here for the Bicycle Conversion Form.https://www.mass.gov/doc/bicycle-conversion-to-motorized-bicycle-moped-affidavit-of-owner/download