I wanted hubby to put little squares of wood under the legs on my B-Line to keep it from sinking into the carpet but he decided all it needed was leveling feet screwed into each leg--wrong! On concrete, it will be able to "walk" so be sure to put non-skid pads under each leg. I would prefer the carpet over concrete myself and just put a little piece of plywood or something under each leg. Extra support under the center of the frame should help, also. I know that would have helped my B-Line.