Abstract: A bicycle padlock has two, independently manipulated, shackles of unequal size, long and short, extending from opposite sides of a body which houses an RFID reader for remote, automatic unlocking. Circuitry in the housing includes a microprocessor which actuates the reader to operate an unlocking motor only within a limited time of receiving a signal from a motion sensor, for battery conservation. A secondary manual unlocking mechanism is operable on failure of the automatic unlocking circuitry.