Abstract: A bicycle (32) includes a seat (20) having a support stem (22), a roller bearing support member (24), a flexible support arm (26), a pair of pivot joints (28), and a pair of seat members (30). The pivot joints (28) comprise ball and socket joints which allow the seat members to pivot about respective sets of axes (X',Y',Z' or X",Y",Z"). Further pivoting motion is provided by the roller bearing support member (24), flexible support arm (26), and by allowing the support arm (26) to pivot. The pivoting motion of the seat members (30) permits the proper range of motion in the rider's (34) sacroiliac joint (D, E) to maintain the flow of CSF in the rider's neurological anatomy thereby enhancing strength and stamina.