If you look at the LSPV you will see three lines going to it, two in the front, and one in the rear. The one in the rear feeds the rear brakes. One of the lines on the front comes from the MC, the other is a return line the goes to a “T” for the front brake system. It is a bias line that changes the bias on the front brakes as the valve works up and down. That is why the front brakes still get air in them if you do not bleed the LSPV. The reason you do it last is the LSPV is the seconded highest component in the system and air travels up, hence the reason you bleed it last.
