Ar sixty I figure I have about 70 per cent of the power and strength I had at thirty. I am not aware of what equipment changes I should make to accomodate my slowly decreasing strength and resiliency, and I haven't tried any. I just keep on keeping on.
I'd say the %'s you gave are about right. I am still learning to just go at a comfortable pace and take longer to get there than I may have years ago. I actually like it better than ever now (at 61) and get excited about touring just planning it.
I camp, use motels, whatever. However, daily shower is required! I've even jumped in half frozen lakes to rinse the sweat off. Very occassionally, of course, it's impossible, and then I have trouble sleeping, being all sweaty, sticky, etc.
I use a lot of other exercises, or I think I would "seize up" from biking only--stretching, weights, rock climbing, hiking, x country skiing, tennis. Jogging ended after the 3rd knee operation. I was told to quit it if I wanted to keep the knee. Duh, no brainer!