Abstract: A securing device is disclosed for the attachment of an assembly, such as a pannier bag, to a structure, such as a bicycle frame. The device includes a clamping member formed by a supporting engagement member and a lever member that exerts clamping pressure in a direction toward the supporting engagement member. The supporting engagement member and the lever member are mounted on a stiff wall with the lever member including a lever arm that is pivotally mounted on the stiff wall so that a compressible bumper is brought into engagement with structure being clamped to establish the engaged position. An adjustable locking mechanism is also provided for engaging the lever arm to releasably lock in the engaged position.