The twin, or tandem, bicycle is designed to be ridden by more than one person. The term tandem refers not to the number of rider but to the seating arrangement (front to back, not side by side). A bike with two cyclists side-by-side is called a sociable.
Beginning in the 1890s, various United States patents were granted for tandem bicycles. Tandem popularity began to decline after World War II until a revival started in the late 1960s.
German-born mechanical engineer Ignaz Schwinn (1860–1945) founded the Schwinn Bicycle Company in Chicago in 1895. Schwinn became the dominant manufacturer of American bicycles through most of the 20th century.