VZ
I don't know anything about the BMW suspension, but in automibles, they can design a complicated linkage system that has the virtual pivot point anywhere they want, not just where the mechanical pivots are. I asume the BMW is like this and they put the virtual pivot point at ground level, this would then have no anti-squat since the tire contact force would pass straight through it. But for our simple swing arm suspensions, the mechanical pivot point is the pivot point, and all forces that do not pass straight through it will try to rotate the swing arm either up or down. If you could compress the suspension enough such that the pivot point was dragging the ground, then the tire contact force would have no effect on the suspension, only the chain force would have an effect and try to bring the rear tire up.
I don't know anything about the BMW suspension, but in automibles, they can design a complicated linkage system that has the virtual pivot point anywhere they want, not just where the mechanical pivots are. I asume the BMW is like this and they put the virtual pivot point at ground level, this would then have no anti-squat since the tire contact force would pass straight through it. But for our simple swing arm suspensions, the mechanical pivot point is the pivot point, and all forces that do not pass straight through it will try to rotate the swing arm either up or down. If you could compress the suspension enough such that the pivot point was dragging the ground, then the tire contact force would have no effect on the suspension, only the chain force would have an effect and try to bring the rear tire up.