Abstract: A tandem adapter frame that attaches to the back of a single-rider bicycle, transforming the bicycle into a tandem bicycle. The rear wheel of the single-rider bicycle is removed from the bicycle and installed on the back end of the adapter frame. The adapter frame is attached to the single-rider bicycle at the seat post and the rear dropouts, resulting in a rigid 3-point connection. This transforms the single-rider bicycle into a rigid frame, two wheel, tandem bicycle with a rider in front and a rider in back. Both riders have pedals. An adapter axle assembly with sprockets on the lower front of the adapter frame serves two functions. It easily attaches between the rear dropouts of the single-rider bicycle using a standard axle and quick-release, and it transmits drive power to the rear crank without modifying the drive chain of the single-rider bicycle.

Abstract: A tandem adapter frame that attaches to the back of a single-rider bicycle, transforming the bicycle into a tandem bicycle. The rear wheel of the single-rider bicycle is removed from the bicycle and installed on the back end of the adapter frame. The adapter frame is attached to the single-rider bicycle at the seat post and the rear dropouts, resulting in a rigid 3-point connection. This transforms the single-rider bicycle into a rigid frame, two wheel, tandem bicycle with a rider in front and a rider in back. Both riders have pedals. An adapter axle assembly with sprockets on the lower front of the adapter frame serves two functions. It easily attaches between the rear dropouts of the single-rider bicycle using a standard axle and quick-release, and it transmits drive power to the rear crank without modifying the drive chain of the single-rider bicycle.