When I stop doing my 3-5 mile brisk fitness walk once or twice a week, I slowly begin to get achiness in my hip joints back again, regardless of whether I'm biking a lot or not. I start to feel creaky and achy in the mornings, especially in my hip joints. (I'm 56)
When you are biking, your leg never really gets flexed back behind you, like it does when you walk vigorously. Biking just doesn't do for my hips what regular brisk walking (with long strides) does. Once I start regular fitness walks again, my hip joint aches go away again.
Just something to consider.