Disclosed herein are various embodiments, including but not limited to a bicycle that includes, among other features, an elongated down tube and a single elongated seat tube, the longitudinal axis of the seat tube intersecting the longitudinal axis of the down tube at a location substantially intermediate between the first and second ends of the down tube, wherein the distance between the spaced apart side outer surfaces of each of the down tube and the seat tube are less than the distance between the upper and lower outer surfaces of each of the down tube and seat tube; additionally including a seat tube, a seat tube sleeve, a crank assembly and a bottom bracket sleeve for mounting the crank assembly, wherein the seat tube sleeve has an upper end, a lower end, and a longitudinal axis extending from the upper end to the lower end; the seat tube being disposed within the seat tube sleeve, the longitudinal axis of the seat tube sleeve intersecting the bottom bracket sleeve.