everyone keeps mentioning hills in this thread, but i live in chicago, one of the flattest places on our globe. the only "hills" we have here are expressway overpasses.
the enemy me for me on my commutes is the wind that often obnoxiously blows along the lake michigan shoreline. on wednesday when the 30 knot winds were blowing, i had to drop down to the 4th gear (52 gear inches) on my alfine 8 IGH (6th is my normal cruising gear (75 gear inches)) to make headway against that awful, awful wind. and unlike hills, wind like that doesn't stop, it just kept blowing and blowing and blowing at me all the way up the lakefront. i can appreciate getting up out of the saddle and powering a SS/FG up a nasty hill along a commute route, but i don't have the realistic option to stand up and power through a 30 knot headwind for all 14 miles of my commute!
i could of course just gear down a SS/FG into the 50 gear inch range, but that doesn't really work all that well for tailwind or wind-neutral days. on wednesday i had that same wind as a tailwind on the ride home, so i bumped my alfine IGH all the way up to 8th gear (99 gear inches) and I was FLYING with the wind all the way home at god only knows what speed. there's no way i would have been able to take advantage of such a ridiculous tailwind like that if i was locked into a 50 gear inch on a SS/FG.
i guess the real point of this thread is that it would be nice to live on a planet without wind. why does the air in my little corner of the world frequently seem to be in such a damn hurry to be somewhere else?