I felt today like gravity could be my friend going uphill. Yes, uphill.
My ride today was through a local neighborhood with moderate ups and downs. The ride concluded with a long (for me), 4 block uphill climb where the grade was fairly constant from bottom to top. This gave me a chance to practice finding an efficient rhythm and pace for the duration of the climb.
The sensation I had during that climb links all the way back to my first post on "hips forward". When I occasionally found that sweet balance point where I was leaning forward into the hill and felt like I was right on top of that unicycle, I felt I had the most efficient transfer of muscle energy into forward motion. The pedaling felt easier and smoother, and I'm sure I was going faster, than if I sat back a bit .
I don't know if this makes any sense, but I think that as I was leaning forward gravity was helping by pulling my body down, but also forward. In short, gravity was helping me move up the hill. My pedaling was easier because it was just keeping the wheel under my body. When my center of mass was back further and I was riding straighter , then gravity pulled me forward less, and pedaling had to move more of that body mass that was no longer being moved by gravity.
That's what it felt like anyway. Hope I can find that sweet balance point more regularly in the future.