Who is More Friendly?

I was thinking about this the other day while on a run.  You know when you are out on your run/hike/bike ride and you pass another person enjoying the same activity?  Who actually acknowledges your existence?

I know when I am running I usually get at least a nod or smile from  my fellow runners.  On a hike I usually get an even better greeting.  Most hikers have a few words of greeting or more.  However, when I pass a biker, I get nothing.  It's as if they don't even see me.  What's up with that?

I really enjoyed the Inter-Runner Acknowledgement Act from Runner's World Daily that touches on this subject.

So the question is, who do you think are friendlier, runners, hikers, or bikers?  And with that, are certain personalities drawn to their sport or do our personalities change depending on the sport we choose.  In other words, are friendly people runners or are we friendly because we run?  The chicken or the egg dilemma.

Now, I am not saying bikers aren't nice, maybe they are just really concentrating.  Weigh in a tell us what you think.