Abstract: A method and system are provided for finishing a concrete floor that exce approximately 50 feet in width. A riding trowel of the type that forms a windrow of loosened concrete material in its wake is positioned on the concrete floor. The riding trowel has a straight edge coupled thereto by a support assembly that positions the straight edge to cross the windrow at a substantially perpendicular angle thereto within line-of-sight of an operator. A power assembly is coupled between the straight edge and the riding trowel for independently controlling vertical and pivoting movement of the straight edge. The riding trowel is driven on the concrete floor and the straight edge is moved along the concrete floor simultaneously with the riding trowel.