Abstract: A semi-recumbent bicycle having a conventional wheelbase. The frame of the bicycle has a unique geometric configuration in that the main tube of the frame is straight such that its axis forms an acute angle with the line of the ground so that the main tube is higher at its rear end than at its front end. This novel arrangement permits the semi-recumbent bicycle to be more easily manufactured and assembled because all of the major components of the bicycle are aligned directly off of the main tube and there is no need, with the exception of the rear triangle which supports the rear wheel, to align and fit together the component parts of the bicycle. Moreover, the semi-recumbent bicycle may be operated by riders of many different sizes because the bicycle seat is adjustable along the main tube toward and away from the foot pedals. The unique geometric configuration also enhances the range of adjustability of the seat and makes it possible to provide a luggage rack which is connected to the back of the seat.