extension and anchor extension in a way that makes this integrated framework appear to be a single seamless part the parts appear to be one molded piece but the frame size and shape is completely customizable these extensions 45 56 60 are from the same mold and are simply cut to length for whatever size bicycle frame is desired the bottom of one part mates to the top of the next part or vice versa alternatively both ends of some parts can make up the bottom or top of other parts the bottom bracket anchor 55 also includes two tabs that are integrated in the molding process these two tabs are secured to the mating parts a down tube 75 and a chain stay element 80 the head tube 70 can be created from a variety of material and fabrication methods such as machining extruding filament winding or any other method known to someone skilled in the art that will yield a tube of the desired shape the head tube 70 can have a round oval pear or a teardrop cross sectional shape the elongation of a teardrop shaped tube can either be constant or it can vary over the length of the tube depending on the tube usage the materials from which the head tube 70 is made can be but are not limited to aluminum carbon and titanium or any other material suitable for use in manufacturing bicycle frames metal head tubes are often employed in carbon frame manufacturing because of the tube 39 s interface.