There's so much nonesense spoken about declining ability due to age.
Lab-study statistics could unneccessarily put off people in a real world.
It really only makes sense in a practical way if you are talking about someone trained to their physical peak at their biological prime.
Take Lance Armstrong in his early 30's as an example. It was true, for him, that it was all downhill from 35 onwards. He'll never be as good again and will probably get progressively worse by the year. That's because he was starting from such a high.
I started riding seriously (I mean Audaxing) 3 years ago at 44 years of age. I'd cycled more than the average person before that but my annual mileage jumped from 1000 (guess) to 5000 miles a year.
I've got progressively quicker in those 3 years and closed the gap between me and the faster boys significantly.
8 years ago I did my first ever 100 mile day ride. It damn near cripled me. Last Sunday I rode a 125 mile (200km) hilly Audax as a social event and could have carried on no problem.
What I'm saying is that, it's not necessarily a depressing thread. In fact, if you are a sedentary, obese, smoker of 40 years of age, you could have 20 years of performance improvement ahead of you if you started cycling.
Those of you who actually achieved their physical peak may see a noticeable decline, even when continuing hard training, but you will always be fitter than me, someone who never reached it in the first place. My upward curve will most likely never cross your downward curve. Lance Amstrong at 77 would whup my 47 year old ass.
Basically it serves you all right for getting in shape so young.