My legs need to be stronger, that's for sure. It's possible I need to be able to climb in a harder gear and lower cadence that will let me keep my heart rate lower. On climbs, I've always geared way down and spun the cranks like crazy! Naturally that sends my HR up.
Even on the flats, I want to be able to ride faster at a lower heart rate. Back to riding the 50/24, and work at doing it for longer and longer stretches. And hope that such high gear/low cadence riding isn't scorching my glycogen stores too fast! I'm not sure, but I think I need work at being a better fat-burner.
Really, I need both high gear/low cadence work and low gear/high cadence work. My natural tendency seems to be for a cadence in the 80s, and my legs just want to move fast. High gear/high cadence, if you're strong enough for it (it can be damaging to the knees if you aren't physically ready for it, so go about it with great caution) would be wonderful. Get out of the way, greased lightning!
Which brings me to another point. Increasing my cruising speed. I've averaged 14+ mph on some of my long Sunday rides, but want to be faster. I need more of those short bursts during weekday rides, when I push the pace a lot harder. I think, when I'm doing intervals to develop speed, push for a specific speed and let HR be what it will.
I can think about it all for a week or two. Meanwhile I think I need a few days off. My legs feel fine, but my breathing doesn't feel relaxed. I guess I'm tired.