I believe the Rune has a linked braking system which requires you to bleed the front brakes as well as the back. The front calipers have 3 pistons the center piston activated when applying the back brake. I believe the order to bleed them in is front L front Rt then rear see attachmentI have that problem now. I use a 4.5 inch tube to push and hold the brake pedal down. When I start the ride, the brake is much improved, but after 50 miles it goes down down down.