I am in my 50's and so is my wife. I just started to get her into bicycling. She can ride, but is certainly afraid of falling to the point that I am absolutely sure that she would never try again if she got injured. As far as I am concerned, the most important thing is, that her fear of falling is smaller than her desire to ride. Because of it, I got her a new, inexpensive MTB. She likes it, because it doesn't have a hign top tube, seat can be lowered so she doesn't have fear of faling and it looks nice, even though it is not expensive. There indeed is IMHO a big difference when a kid is learning how to ride versus middle aged adult. The kid is made of rubber, doesn't know enough to be scared and the peer pressure is for him/her to ride. None of these forces work for you in case of most of us non-kids. I know that she will gain the proper skills in time, and she can then decide if she wants yet another bike, but for now it feels safe, is easy to ride because of the gearing and you can ride it almost anywhere. The advantages of the other bikes at the moment is higher speed on the road - hardly a consideration for a beginner. I hope this is relevant.