Recumbent bikes are expensive, at least when I last looked at them. I hope you got a good price. I had back problems and knee injuries early in life. A physical therapist I saw in my 20s told me that she saw 2 kinds of patients: Active people with joint problems that needed work. Lifelong sedentary people who had problems from not exercising She said of the two groups, Group 1 was definitely much better off. Don’t give up, get yourself to a physical therapist. Get evaluated by a doctor of physical therapy and have them write your treatment plan for you. It is all science and it can do miracles for your back and knees. Since it is science it improves over the years.