Where Can I Find Replacement Black Knobs for My Bones Rack? Philip Cowles March 30, 2018 14:11 Follow Replacement rack parts, including Bones knobs, are available on our Replacement Parts page. Related articles I Am Worried That Trunk Rack Will Scratch My Car. I Need to Replace the Top Hold-Downs on My Bones Rack. Why Won’t the Replacement Rack Straps on the Accessory Page Work? How should I position my bike when mounted on my bike rack? Can I Use a Cover on My Bike While It Is on a Saris Rack? Comments 0 comments Please sign in to leave a comment.