Section 21204 Of Article 4. Operation Of Bicycles From California Vehicle Code >> Division 11. >> Chapter 1. >> Article 4.
21204
. (a) A person operating a bicycle upon a highway shall not
ride other than upon or astride a permanent and regular seat attached
thereto, unless the bicycle was designed by the manufacturer to be
ridden without a seat.
(b) An operator shall not allow a person riding as a passenger,
and a person shall not ride as a passenger, on a bicycle upon a
highway other than upon or astride a separate seat attached thereto.
If the passenger is four years of age or younger, or weighs 40 pounds
or less, the seat shall have adequate provision for retaining the
passenger in place and for protecting the passenger from the moving
parts of the bicycle.