75 Pa.C.S. § 3504: Riding on pedalcycles.

(a) Use of seat by operator.--A person propelling a pedalcycle shall not ride other than upon or astride a permanent and regular seat attached to the pedalcycle.

(b) Number of riders.--No pedalcycle shall be used to carry more persons at one time than the number for which the pedalcycle is designed and equipped except that an adult rider may transport a child in a pedalcycle child carrier which is securely attached to the pedalcycle or in a trailer which is towed by a pedalcycle.