A system for shaping media for printing by a media width printhead is provided having a media width printhead of fluid ejection nozzles defining a media width print zone, input rollers disposed for transporting media into the print zone at an angle to a plane parallel with the print zone, output rollers for transporting media out of the print zone at an angle to a plane parallel with the print zone, and an elongate platen for supporting and shaping the media as the media is transported through the print zone. The platen has a series of ribs disposed upstream of the print zone and a series of ribs disposed downstream of the print zone. The ribs are configured so that the transported media adopts a constrained curved path past the nozzles through contact with the ribs in the print zone.