I tore my ACL in my young twenties. In my late 20's, while boxing, I tore both cartilages in the same knee. Cartilage tears have increased risk if you have a blown ACL. Therefore it is prudent to fix the ACL before you have more problems with cartilage. After surgery to repair I found that I still tore cartilage on a yearly basis for 5+ years. I had an MRI a couple of years ago at the age of 48, and the doctor was amazed that my knee looked good inside, especially considering the additional tears ( which were all small).

I understand that I need to cycle to keep everything clean inside my knee. Additionally if I stop training I have an increased risk of being injured. So I try to bike alot.