A round baler for forming round bales of crop material includes a crop pickup which feeds crop material rearwardly toward a bale-forming chamber defined by a series of rollers in combination with a bale-forming section of a series of side-by-side baler belts. The series of rollers include front and rear floor rollers which rotate in the same direction, as well as an upper stripping roller and a powered feed roller. The powered feed roller cooperates with the front floor roller to define a crop inlet, and the feed roller and the front floor roller aggressively feed crop material into the bale-forming chamber. The front and rear floor rollers cooperate with the bale-forming section of the baler belts and the upper stripping roller to define an open initial bale-forming chamber. As the bale grows, the bale-forming section of the belts expands and the bale is supported by the rear floor roller without support from the front floor roller. The stripping roller is maintained in engagement with the bale, and strips crop material off of the baler belts downstream of the bale-forming section of the belts. The powered feed roller is mounted between a pair of pivotable arms which provide movement of the powered feed roller toward and away from the front floor roller in an arcuate path, to accommodate increases in thickness of the crop material supplied to the crop inlet. A spring is interconnected with the powered feed roller for biasing the powered feed roller toward a normal operating position, to maintain the powered feed roller in engagement with the crop material as the powered feed roller is moved toward and away from the front floor roller and to maintain the aggressive feeding action provided by the front floor roller and the powered feed roller. The arms may be pivotable about a pivot axis coincident with the axis of rotation of the stripping roller, so as to facilitate mounting and driving of the powered feed roller.