Maybe it is cast iron? Equivalent to a ground anchor.
Mine is attached to a (thick) wooden stair post. If someone saws through to nick my bike it is ample enough to justify the insurance company paying out - noise would be heard in the whole building, time taken to saw through...
Mine is attached to a (thick) wooden stair post. If someone saws through to nick my bike it is ample enough to justify the insurance company paying out - noise would be heard in the whole building, time taken to saw through...