Abstract: A bicycle frame for bicycles designed for structural strength and for positioning of a chain sprocket above the lowermost portion of the frame. The frame is constructed with a looped tube assembly with a front tube loop connected to a head tube and wheel fork assembly forming a quadrilateral structure of generally triangular shape, and a pair of rear tube loops forming a pair of parallel quadrilateral structures of generally diamond shape, with the front tube loop and rear tube loops being mutually interconnected on a sprocket shell. The looped tube assembly has seat and chain stay bracing, and brackets for mounting a rear wheel between the pair of rear tube loops.