I have addressed this previously so I hope nobody minds hearing about it again. I too have knee problems and had to sell my ST1300 because of my knees. I thought the F6b would be better so I bought one. After riding a short time my knees were hurting again and I was afraid I would have to sell it until I put on the Kuryakyn II pegs. The pegs saved my riding. Because of them I can sit in about five different positions including lifting the bottom of my butt completely off the seat while pushing hard on the pegs. I'm not concerned about braking because the bike has linked brakes so pulling the brake handle engages both front and back. I only use the pegs when I don't plan on braking anyway. The ability to straighten my legs with the pegs has definitely helped my knees and allowed me to keep riding.
https://imgur.com/a/kNdPg