The first person to tour the world did it on a single speed.
Reinhardt bicycle
Catalog #: 311,533, Accession #: 148,650
In collection
From the Smithsonian Collection
The donor, Fred A. Birchmore, a resident of Athens, Georgia, bought this bicycle in Gotha, Germany, in July 1935. An "Original Reinhardt," it was made by Fahrradfabrik Otto Reinhardt, Bielefeld, Germany, and was bought for 67 reichsmarks. In the course of the next two years Mr. Birchmore rode it through western Europe, eastern Europe, Crete, Cyprus, Egypt, Iraq, Iran, Afghanistan, India, Siam, Indochina, and the Philippines, before pedaling his bicycle home across the United States from California.
It has been estimated that his travels covered approximately 40,000 miles, of which about 25,000 were on the bicycle, and the rest by boat. Approximately four saddle covers and seven sets of tires were worn out during the journey. The present tires were purchased from a shop in Calcutta, India.
Link to the Smithsonian's article