My bike has one of those metal rear racks with a spring-loaded clamp, the kind you can pull open and let snap back shut. I noticed the space had this intense echo because of all the concrete, so I pulled the rack clamp up, let it go, and it snapped shut with this sharp metallic crack. The sound bounced off the walls and ceiling under the overhang, mixing with the rain and the wind, and it made this weirdly satisfying, dramatic noise.