A lock, comprising: a shackle comprising: a plate portion having a length in a longitudinal direction, a thickness (310; 310') in a lateral direction, and a first width (304; 304') in a transverse direction, wherein the length is greater than the first width (304; 304'); and a pair of longitudinally-offset legs extending from the plate portion in the lateral direction, wherein the legs are fixedly and immovably secured to the plate portion, and wherein the plate portion prevents relative movement of the legs; wherein each leg of the pair of longitudinally-offset legs includes a corresponding and respective foot, and wherein each foot includes a corresponding and respective notch; and a crossbar comprising: a pair of longitudinally offset openings, wherein each foot is received in a corresponding and respective one of the openings; a pair of deadbolts, wherein each deadbolt is in an extended position in which the deadbolt is engaged with the notch of a corresponding and respective foot; and a locking mechanism configured to selectively retain the deadbolts in the extended positions thereof, thereby selectively securing the shackle to the crossbar; wherein in use that the plate portion is offset from the crossbar by an offset distance (302; 302') such that a portion of each leg is exposed, and wherein an exposed portion of each leg has a diameter (308; 308'); wherein the first width (304; 304') of the plate portion is greater than the diameter (308; 308') of the exposed portion of each leg; characterized in that the first width (304; 304') is greater than the thickness (310; 310'); wherein the first width (304; 304') of the plate portion is greater than the offset distance (302; 302'). a shackle comprising: a plate portion having a length in a longitudinal direction, a thickness (310; 310') in a lateral direction, and a first width (304; 304') in a transverse direction, wherein the length is greater than the first width (304; 304'); and a pair of longitudinally-offset legs extending from the plate portion in the lateral direction, wherein the legs are fixedly and immovably secured to the plate portion, and wherein the plate portion prevents relative movement of the legs; wherein each leg of the pair of longitudinally-offset legs includes a corresponding and respective foot, and wherein each foot includes a corresponding and respective notch; and a plate portion having a length in a longitudinal direction, a thickness (310; 310') in a lateral direction, and a first width (304; 304') in a transverse direction, wherein the length is greater than the first width (304; 304'); and a pair of longitudinally-offset legs extending from the plate portion in the lateral direction, wherein the legs are fixedly and immovably secured to the plate portion, and wherein the plate portion prevents relative movement of the legs; wherein each leg of the pair of longitudinally-offset legs includes a corresponding and respective foot, and wherein each foot includes a corresponding and respective notch; and a crossbar comprising: a pair of longitudinally offset openings, wherein each foot is received in a corresponding and respective one of the openings; a pair of deadbolts, wherein each deadbolt is in an extended position in which the deadbolt is engaged with the notch of a corresponding and respective foot; and a locking mechanism configured to selectively retain the deadbolts in the extended positions thereof, thereby selectively securing the shackle to the crossbar; wherein in use that the plate portion is offset from the crossbar by an offset distance (302; 302') such that a portion of each leg is exposed, and wherein an exposed portion of each leg has a diameter (308; 308'); wherein the first width (304; 304') of the plate portion is greater than the diameter (308; 308') of the exposed portion of each leg; characterized in that the first width (304; 304') is greater than the thickness (310; 310'); a pair of longitudinally offset openings, wherein each foot is received in a corresponding and respective one of the openings; a pair of deadbolts, wherein each deadbolt is in an extended position in which the deadbolt is engaged with the notch of a corresponding and respective foot; and a locking mechanism configured to selectively retain the deadbolts in the extended positions thereof, thereby selectively securing the shackle to the crossbar; wherein in use that the plate portion is offset from the crossbar by an offset distance (302; 302') such that a portion of each leg is exposed, and wherein an exposed portion of each leg has a diameter (308; 308'); wherein the first width (304; 304') of the plate portion is greater than the diameter (308; 308') of the exposed portion of each leg; characterized in that the first width (304; 304') is greater than the thickness (310; 310'); wherein the first width (304; 304') of the plate portion is greater than the offset distance (302; 302').