I would have to say this ride. Not physically but mentally challenging. I hit a spot where it looked flat but was actually a 7% grade (Damnation Alley for the locals). I could see the mountain road above and thought to myself, "if I'm struggling on this flat part, I might not make it when I hit that road!".
That was the tough part of the ride. Once I hit Glen Oaks, it was actually much easier. Just a mental thing optical illusion type thing.
12,000 of climbing, most of it in the first 72 miles/ 114 miles total.
It was right around here that I had doubts.