Never? As people age, their muscles don't deliver the same power over time as they did when they were younger. I don't think it's only a matter of conditioning. I'm in reasonably good shape, but I have noticed a difference, since my late-40s, in my ability to climb long, steep hills. It's tougher now. But easier to cope having switched from 24-34T.

22-34T is my lowest gear right now, and it's adequate for most hills; but not nearly low enough for the very long 18% or 20% slope I attempted a couple of years ago. I would like to try a 20-tooth granny, or even a 17 or 18.

According to Michel Gagnon's web site, the quad isn't compatible with STI shifters... and if that's true, there is no quad in my future! I am hoping to be able to swap the 22T for something smaller.