Abstract: A collapsible bicycle includes a body frame including a front wheel rotatably mounted on a first end portion thereof, and a seat tube fixedly mounted on a second end portion thereof. A rear frame includes an upright tube disposed beneath the seat tube, a pair of seat stays each extending from the upright tube, a rear wheel rotatably mounted between the pair of seat stays, and a pair of supporting brackets each having a first end portion fixedly mounted on a corresponding one of the pair of seat stays and a second end portion located at a position flush with the rear wheel. A pivot mechanism is pivotally connected between the seat tube and the upright tube such that the upright tube can be pivoted relative to the seat tube, thereby pivoting the rear frame toward the front wheel of the body frame to a position where the second end portion of each of the two supporting brackets together with the rear wheel can be supported on the ground synchronously.