Yes, the arms are different, but I see little logic in comparing A's and B's in the first place, different in so many ways (WB, Track, arm length, TB length, F/R weight, aero, etc, etc) its almost pointless. I thought the premise I was responding to was how one could compare TB's pf same diameter from different manufacturers, and to repeat my original point, there should be little difference in the effective rating of any bars of similar diameter on the same car, even if the manufacturers each use different measuring metrics, unless the wheel offset is changed .