A three-person bicycle (20) having two of the riding positions situated between a front wheel (22) and a rear wheel (26), and the third riding position situated behind the rear wheel (26). Bicycle (20) includes a front first seat (34), a middle second seat (36), and a third rear seat (38) connected to a frame (32). Front seat (34) and second seat (36) are located on frame (32) between front axle (24) and rear axle (28). Third rear seat (38) is connected to frame (32) behind rear axle (28) and rear wheel (26).

A close-coupled tandem bicycle is described with a shorter wheelbase than a standard tandem bicycle and with the front and rear riders positioned closer together for easier communication and interaction between them. Two pedal cranks drive the rear wheel through a sprocket-and-chain drive. Both the front and rear passenger can steer the bicycle. A main handlebar with long handgrips extends rearward within easy reach of the rear passenger. A secondary handlebar attaches to the main handlebar and extends in front of it for use by the front passenger. The height and forward extension of the secondary handlebar is adjustable independently of the main handlebar so that both passengers can adjust the seat and the handlebars to their liking. The tiding positions can be adjusted to allow two riders of different sizes, such as a child and an adult, to ride together in comfort. The close-coupled seating arrangement gives a child riding in the front seat a greater sense of safety than the head-to-tail arrangement of standard tandems. A blind or handicapped passenger can also ride in the front or rear position and truly participate in steering and controlling the bicycle with the increased sense of security of having another rider in close proximity. The fore-and-aft adjustability of the riding positions also allows two riders to move very close together so that they can ride in a closer, almost intimate, riding position perfect for taking romantic bicycle rides together.

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.

Tricycle and intermediate frame for tricycle. The tricycle includes a rear axle, rear wheels coupled to free ends of the rear axle, a rear seat, and a rear frame coupled to the rear axle and to the rear seat. A front frame includes a fork tube, and the front frame and the rear frame are detachably connectable to each other. The tricycle also includes a handlebar, and a fork coupled to the handle bar. The fork is rotatably coupled to the fork tube. A front wheel includes pedal cranks and is rotatably coupled to the fork. A second seat and a holding element are also included. The intermediate frame is arranged to support the second seat and the holding element, and is detachably coupled between the front frame and the rear frame.