A crop harvesting header with a cutter bar (11) and a draper assembly has a draper canvas (32) driven by a drive roller (30) with a cylindrical roller body having an outer surface (302) surrounding an axis of rotation (303) of the roller for engaging an inner drive surface (304) of a canvas wrapped therearound. The roller has a plurality of ribs (305) arranged on the outer surface of the roller body extending along a part of the body in an axial direction and angularly spaced around the outer surface. The ribs have a height less than 6 mm and a width less than 6 mm arranged such that the ribs do not engage into any recesses in the drive surface of the canvas.
