say "cyclist" and not "biker" or "rider." cyclist has a very elite, roadie connotation. like you ride in spandex on weekends among people with whom you hobnob. let them think that you are a road cyclist. its elite, like golf, but more active. let them think "lance," not "messenger."

then again, why the hell are you putting your hobbies on your resume? if you need to fill space, make up jobs and get your friends to cover for you as references if need be.