Hum, not so sure about that. I've been racing since I was about 42. Now at 56, I rode 40 KM in the 53s twice last year having never gotten below 54:30 till after 50. I just did a FTP test over the weekend and found five watts more than I had last year at this time. Perhaps if we rode at our genetic potential we would see the decline you speak of but it seems there's always something left to add to the mix to keep declining performance at bay. I'm not that unusual either. There seems to be a group of outliers who are able to improve their performance into their 60s. STer Kevin Metcalfe apparently never rode under 50 minutes until he was over 50 years of age. And, alas, in my age group Gary Painter set a new American record in the 40 KM with a time of 50:58 if I remember correctly. There are others of note even in your state of TX who are riding faster in their late 50s than they ever have. Part of it is equipment for sure, but the rest of it is improved FTP. See you at the TX TT again this year.