I usually give the head nod, only to be snubbed (happened this morning). I say hello or good morning whenever possible but roadies always ignore me (except for once, when they were in a peloton and all waved). I get more pleasant responses from the people I pass waiting for the bus or taking the trash out etc. They always exchange pleasantries with me (provided we make eye contact). The roadie thing is kind of annoying. I sat at a stoplight with one (it may be the same guy each time), said "goodmorning" only to be not replied to and he zooms through the busy intersection at first chance.
The waving thing reminds me of when I was younger:
My older brother and I were at my parents driveway when we saw a harley rider come down the street. We both waved and he decided to use both hands to wave back. Unfortunately there is a slight bend in the road and he went into my parents yard, hit the wellpump and bike and rider flew down the hill in there yard.