I'm 61, and have only been cycling with any kind of seriousness for about 15 years. Mostly mtb for the first few years and then "gravel" riding ever since. I'd say my endurance is as good if not better, than ever. I do tons of climbing, due to where I live it's unavoidable. That said, I don't track my stats at all, I just go by how I feel. As for speed, I have no idea, except that I've always been the slowest guy out there! My main issue is, I need to make sure I'm doing other things than just riding for exercise, but it's all I want to do
