A bicycle frame assembly including a down tube and a monolithic down tube support. The down tube support preferably defines a pocket configured to receive an end portion of the down tube such that the tube support overlaps at least a portion of a side surface of the end portion of the down tube. In one embodiment, a weld bead joins both of the tube support and the down tube. Preferably, the down tube support also defines an opening configured to receive and support a pedal crank assembly relative to the bicycle frame. Furthermore, preferably the down tube support also includes a pivot mount portion configured to rotatably support a sub-frame of the frame assembly or a rear shock absorber.