It's illustrated in diagram C, in your photo: the tube is clamped between the mudguard (reinforced by the flat plate) and the curved plate.
It doesn't seem to work though. What holds the curved plate to the bridge? The screw doesn't seem anywhere near long enough either
@dots started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
It's illustrated in diagram C, in your photo: the tube is clamped between the mudguard (reinforced by the flat plate) and the curved plate.