A ratcheting whirr
A cyclist's faint silhouette
It's a bike ninja!
See him up there? Yeah, neither do I. There are two other stragglers who refuse to put their bikes away. One's a well-lit, pannier-toting guy who goes eastbound then south. Then there's this guy who travels west. Black bike, dark clothes, mammoth backpack and either a hipster cyst (knog frog) or a similarly dim, useless single white LED thing on his handlebars.