Do you have a standard or compact front ring setup? Are you on the little or big chainring, typically? Those questions would help people give you better advise.
Thanks. Like I said, I don't really know a lot of the 'whys and hows' of this type of questions, though I do want to learn!
I have a 2-chainring set-up in the front. I do spend a lot of time in the big ring, even while climbing, but at the end of a long, hard ride I also spend time in the small chainring, on one of the 3 larger chainrings in the back (yeah, my endurance is the #1 problem area I am working on right now). That makes it a little more confusing to me, since it seems like I do utilize the full array of options available to me right now, just need more difficult gears to kick into on flats earlier in the ride?