 This allows the rear triangle on both sides of the wheel to be rigidly connected together as one piece, before attaching to the connecting links of the four-bar.This significantly increases lateral and torsional stiffness of the rear, often a weakness of four-bar designs, and reduces the load on the pivots, connecting links and joint between rear axle and frame.The "Virtual Pivot Point" or VPP, is the name given to a four-bar linkage suspension with relatively short links connecting the rear triangle to the frame.