A bottom bracket unit including a bottom bracket axle (1), at least one bearing (2, 3) that receives the bottom bracket axle (1) in a rotatable manner, and an optical detection unit (11), by which a rotational speed of the bottom bracket axle (1) can be detected. The optical detection unit (11) measures at least one signaling device (12) that is rotationally fixed to the bottom bracket axle (1). The aim of the invention is to provide a bottom bracket unit that can also detect the rotational direction of the bottom bracket axle in addition to the rotational speed of the axle. This is achieved in that the optical detection unit (11) has two optical sensors (17), with one of these sensors (17) providing a signal that is phase-shifted with respect to the other sensor (24) having a fixed phase difference, in particular with a phase difference of 90°.