Fitness walking really eliminates hip joint aching for me. When i bike too much and stop walking regularly, my hips get achy and stiff. I go back to brisk walking about 3-5 miles, 2 to 3 times a week, and that cures it after a couple of weeks. I know I must continue my walking in order to keep my hip joints happy.
The reason is that when you walk brisky (not just schlepping around the house or in an office) your leg extends BACK with each long step and straightens the hip joint all the way back. In biking, your hip joint stays bent even when your leg is straight....because you are still sitting, remember. In biking, your hip joint never flexes all the way straight and back.
The fitness walking really works for my hips. I make sure to let each leg go as far back as possible while I walk, taking long brisk strides.