“Like a Hawk in its Gyre” is up at Redstone Science Fiction, February 2011 (issue #9), edited by Michael Ray.
The bicycle noticed someone was following before Kurt did. Watching for a tail was a habit he’d finally broken himself of, but not before the bicycle’s impressionable brain had picked it up. Its low warning hum sent a thrill of adrenalin through him, giving power to the part of his brain that wanted him to sprint away.
Update: “Like a Hawk in its Gyre” has been reprinted in audio form on Escape Pod, read aloud by Tim Crist.