Note to the bike-porn fans at the Brattle: with all of its shots of toned, sweaty shoulder muscles arched over handlebars, you may be the only audience able to get off on this veloci-thriller. Director David Koepp's tale of a thrill-seeking courier who accepts the wrong rush-delivery envelope and attracts various pursuers could have been called The Bike Messenger Who Knew too Much. But don't expect it ever to top the Sight & Sound poll: for a film that claims to be propulsive, its 85 minutes drag on, dithering in and out of boring subplots that add up to little. The performance by Joseph Gordon-Levitt provides a bright spot, though, and he musters all of his charm to improve a shitty script. Likewise Michael Shannon, who is obviously giddy to be playing a silly caricature of a corrupt cop after so many serious roles. Someone should have heeded the "brakes are death" creed of Gordon-Levitt's messenger and slammed them on while this was still a script.