A convertible transport system including a seat portion, a back support portion, and a pivoting mechanism coupled to the seat portion and to the back support portion. The pivoting mechanism is configured to adjust and lock the back support portion relative to the seat portion, the pivoting mechanism having three operative states: a free pivoting state allowing the back support portion to pivot relative to the seat portion about an axis; a ratcheting state allowing the back support portion to only pivot toward the seat portion about the axis; and a locking state in which the pivoting mechanism is locked to thereby prevent a pivoting movement of the back support portion relative to the seat portion.