I make it a point to nod to each of every person eye pass when road biking. I look them straight in the eye so they can't miss me. Some nod back... even if it does look like such a unnatural act for them to be polite. It's almost like I'm their mom teaching them manners. When I'm running on the bike path and someone passes me without calling it I like to say "On my what!?". Just a friendly reminder that they aren't f***king special, and don't own the bike path. I've met a lot of nice road riders though. Just have to break the ice with them first.