Air passenger boarding bridge or escalator

Boarding bridge or stairs (4) with a front transition (1), wherein the transition (1) comprises a bellows with front bumpers (8) and a floor (12), wherein the bellows comprises a plurality of bellows elements (7), wherein the transition in the region of the floor (12) has at least one guide rod (20) for longitudinally slidable guidance of several bellows elements (7), wherein the guide rod (20) in the region of the bumper (8) is bent in an arcuate manner in the direction of the floor (12).