So I may not be quite qualified to comment here, but at 36 years old I have observed my father age extremely well. Now quickly approaching 70 he has become an avid white water kayaker. He first went on a rafting trip when he was 50, loved it and has progressively become more and more obsessed. So, its not bikes, but it was something totally new to him, and now he is very, very skilled at whitewater kayaking.
Keep riding and remember, it takes practice to get good at something.