A bicycle rack assembly comprising a rack-side unit, a base which is mountable to the rack-side unit, and a locking assembly, the locking assembly comprising a movable member configured to be retained by the base, the movable member comprising a base-side lock structure which is engageable with a rack-side lock structure of the rack-side unit for locking the base to the rack-side unit,
- wherein the movable member comprises an insertion recess configured for at least partly receiving a corresponding key device therein in an insertion direction for disengagement of the base-side lock structure from the rack-side lock structure,
- wherein the locking assembly is provided with a security mechanism configured to inhibit disengagement of the base-side lock structure from the rack-side lock structure otherwise than by use of the corresponding key device,
- wherein the bicycle rack assembly comprises the corresponding key device,
- wherein the security mechanism comprises at least one blocking element which is resiliently suspended into the insertion recess from a main body of the movable member so as to be movable between a blocking position and a releasing position by the key device when inserted into the insertion recess,
- wherein in the blocking position the at least one blocking element is configured to block a disengaging movement of the movable member with respect to the base associated with disengagement of the base-side lock structure from the rack-side lock structure,
- wherein in the releasing position the at least one blocking element is configured to allow said disengaging movement, and
- wherein the blocking element is configured to convert an actuation by the key device in the insertion direction to a movement of the blocking element from the blocking position to the releasing position.