Notes
Since there was about 2 inches of fresh slick snow on most of the trail along with some icy areas, I was afraid that the Hansons 11:30 (for flats) pace I'm using would be too much, so after the first mile, I figured I'd try running by HR instead -- aiming to keep it in my 150s (upper Zone 2), since the Magic Spreadsheet tells me 157-163 for long runs, and I know 150s should feel OK.
So, I guess that was a bit aggressive, since I nailed my paces no problem. I would glace at pace about once a mile (mainly because that was the screen showing me how far I had gone), but I mainly stuck to watching HR, aiming for 152-156 for the first 10 miles. I allowed it to go to low 160s in the uphill mile 6, and then I figured that for the final 5 miles, I could hit 160ish since I would likely have cardiac drift, etc. I was definitely working hard the last 4 miles, but I kept pushing it, hoping to still hit my Hansons paces since I'd done it so far. Suprisingly, I guess I didn't have that much cardiac drift at that point, as I was inadvertently speeding up! The last couple miles were hard, but doable. I think 150s is probably a good HR zone for me for hard work on a long run.
I'll be curious to see how much faster I'd have run if the ground had been in better shape. Mile 8, the turnaround mile, had two passes through the 1/4 mile train tunnel which was perfectly smooth and clear, and I watched my HR in there to make sure I held steady effort, but I was speeding up by quite a bit, as is evidenced in the time that mile (10:45). If I want to run by effort/HR for Hansons 11:30-11:40 pace, I'll need to reduce the HR target, especially if the ground is smooth.