Missouri Revised Statutes Title XIX. Motor Vehicles, Watercraft and Aviation § 300.345. Riding on motorcycles, additional passenger, requirements

1. A person operating a motorcycle shall ride only upon the permanent and regular seat attached thereto, and such operator shall not carry any other person nor shall any other person ride on a motorcycle unless such motorcycle is designed to carry more than one person, in which event a passenger may ride upon the permanent and regular seat if designed for two persons, or upon another seat firmly attached to the rear or side of the operator.

2. The operator of a motorized bicycle shall ride only astride the permanent and regular seat attached thereto, and shall not permit more than one person to ride thereon at the same time, unless the motorized bicycle is designed to carry more than one person. Any motorized bicycle designed to carry more than one person must be equipped with a passenger seat and footrests for the use of a passenger.