Originally Posted by the sci guy

whenever i go over a bump where my rear wheel drops down hard (like uneven sidewalk, or sometimes rough parts of the path like where lots of tree root bumps are) there is an awful sound - I think it might be my chain slapping again the top of the cog? Is that a thing? Is there a way to stop it or is it just part of riding SS? My chain doesn't come off.
I'm 99% sure its not the sound of my CO2 cartridge banging around in my bag - because I know what that sounds like.