I would have to say that I felt it more anaerobically. I was (and still am getting pretty good leg burn at the top of a good climb. The posture is quite a bit different on the bike from the spinning bike. I am in a more forward position on the bike. I rode 150 miles last weeks and am beginning to to feel a lot better. I am riding 15 mile in the mornings and feel really good. I did a 25 mile ride on Sunday and my legs felt pretty dead for most of the day. I am going to try a couple of 25 - 30 mile rides this weekend to see if I am improving.