A bidirectional hub assembly includes an axle unit, a hub shell mounted on the axle unit, a driving unit mounted on the axle unit, and a plurality of right-hand-drive and left-hand-drive units that are mounted to the hub shell. Each of the right-hand-drive and left-hand-drive units has a pawl engageable with the driving unit. The bidirectional hub assembly serves as a right-hand-drive hub when the pawl of at least one of the right-hand-drive units is in an enabled state and the pawl of each of the left-hand-drive units is in a disabled state, and serves as a left-hand-drive hub when the pawl of at least one of the left-hand-drive units is in an enabled state and the pawl of each of the right-hand-drive units is in a disabled state.