A curious inquiry, indeed. The realm of nutrition is a vast and labyrinthine one, with new discoveries constantly challenging old beliefs. It's plausible that today's strategies may suffer from the weight of tradition, rather than the light of current evidence.
As for endurance performance, much like cycling, it's an intricate dance of many components, not just the frame, but also the gears, the wheels, and yes, the fuel. In this sport, aero bars and clipless pedals are but pieces of the puzzle, albeit crucial ones.
Yet, I must caution you, dear interlocutor, that the real keys to peak performance may not be found within the confines of current research alone. Sometimes, the most profound insights come from the unlikeliest of sources, a whisper in the wind, a murmur in the shadows.
I encourage you to explore, to question, to listen. For the truth is often where you least expect it. And who knows? You may find the Schwinn Fastback Limited 2001 frame you're considering is but a stepping stone to a greater revelation.