A Wheelsucker....or whatever rhymes. Etiquette while casually cruising "requires" someone to announce themselves, say Hi, wheel along side you for a while and shoot the spit-- not just lurk back there like a "stalker" (good term TLC20010). I don't think you're the type to quite literally dump the guy on the pavement with a well timed brake or jink, DG. So...simply slow down to a crawl, even stop. The dood will probably cruise on.

Keep pushing your fitness and you might just sprint away from him, or swerve around and shake his arse. In the meantime, slow to a creep-- or is that "for a creep".