The invention relates to a bicycle, with a bicycle seat assembly rotatably connected to the bicycle. Rotation movement of the bicycle seat assembly is possible, seen in the driving direction, to the left and to the right side and is independent of the steering movement of the bicycle. The axis of rotation of the bicycle seat assembly is arranged in front of the axis of the bottom bracket, seen in the driving direction, and the seating surface of the bicycle seat is arranged behind the axis of the bottom bracket, seen in the driving direction. The rotatable bicycle seat assembly enables an upright riding position by dodging the cyclist's leg pedaling downwards through a rotational movement. At the same time it supports the hip side of the other leg. The driver is supported by the bicycle seat even in the upright riding position.