I don't seem to exert nearly as much effort when climbing with my Tange frame, and the weight difference between that bike and my 4130 bike hasn't been a factor. I hear that it has something to do with frame flex and pedaling cadence. But it can't all come down to the tubing, can it?

If I can sell all the 80s vintage frames that I've picked over the years and left unbuilt for one reason or another, mostly sizing, I might just get one of these.