(a) A person operating a bicycle shall ride upon the sidewalk rather than the roadway when sidewalks are available, except that no person shall ride a bicycle upon a sidewalk upon or along which signs have been erected by authority of Council or other duly designated local authority prohibiting such bicycle riding, or within a business district. At no time shall a person under the age of eleven years operate a bicycle on a street.
(b) Whoever violates any provision of this section is guilty of a minor misdemeanor on a first offense; on a second offense within one year after the first offense, the person is guilty of a misdemeanor of the fourth degree; on each subsequent offense within one year after the first offense, the person is guilty of a misdemeanor of the third degree.