This is pretty interesting, espeically your results of new Alum vs old steel. What's the weight difference on the bike? Gearing difference? If the old bike is 6 speeds and the new is 11, you would likely find a better "sweet spot" in your pedal cadence that might give you the edge- I could easily see that making a few % difference. However, take the wheels and groupset off the Felt and put it on the steel frame, and I think the difference would be negligible. Any thoughts?