Bike trailer frame structure

A bike trailer frame structure, comprising:

• a rear frame comprising a left side tube, a right side tube, and a connecting tube connected between said left side tube and said right side tube;
• and
• a base frame comprising a left bracket, a right bracket, a front bracket connected between said left bracket and said right bracket and a rear bracket connected between said left bracket and said right bracket, said base frame having a rear side thereof movably connected to a bottom side of said rear frame, one of said left bracket and said right bracket of said base frame having a front side thereof movably connected to a tow bar that has a front side thereof used to connect a bicycle;
• wherein:
• said left bracket and said right bracket of said base frame each have an opposing rear side respectively connected to a left pivot base and a right pivot base, said left pivot base and said right pivot base each having a fixing hole (fixing groove) respectively connected to a bottom side of said left side tube and a bottom side of said right side tube of said rear frame through a respective left positioning element and a respective right positioning element;
• thereby, when said left positioning element and said right positioning element are released, said rear frame is able to pivot toward said base frame and fold, and is able to pivot in the direction opposite to said base frame and then fix said left positioning element and said right positioning element to the said fixing holes (said fixing grooves) of said left pivot base and said right pivot base.