[3] As a thematic topic, bicycles are notable for the wide variety of subjects that they are used to illustrate.
[9] The United States issued a special delivery bicycle messenger stamp in 1902.
Bulgaria issued a cycling stamp as part of a set commemorating the Balkan games of 1931.
Denmark issued a stamp showing King Christian X on horseback as part of his silver jubilee celebrations in 1937; in the background of the street scene are three cyclists.
These early issues illustrate the wide variety of subjects depicted on bicycle stamps.