Well, thank you, then, just thank you. This race the 3s were in their 30's I think, but we have some really fast old chicks in the area too. I actually would also have been 4th in the 3s (only 4 people raced), 4th in the 4s and 4th in 40+.
But yes I think that you are articulating something I have been doing without really thinking it through; for TTs it makes more sense to race age than category.