Cycling - Headwind in Every Direction! Here's why.

I came up with the simple explanation.

Stick your head out of the window next time you're driving on the highway.  That 100km/h (60 mph?) gust you feel is not really wind, but you moving through the air at 100km/h.

And that is why you feel a headwind on the bike.

If the air is completely still and you are moving 30km/h through it - the amount of air hitting you is exactly what it would be if you were standing around in a 30km/h wind! 

The only way you'll feel like there isn't a headwind?  If the air is moving faster than you in the direction you are moving.

So really, next time you feel the headwind where you don't think it should be, just remember it's your reward for going so darn fast.  Congrats!