Shimano dual sided power meter accuracy

Equipment
4

The left side is accurate. The problem arised because the right crankarm is asymmetric, and this asymmetry is hard, almost impossible to compensate for. This is not 4iii’s fault, it’s on Shimano. And it is shared by all right-side power meters based on modern DuraAce and Ultegra cranks, including Shimano’s own (courtesy of Pioneer).