I had knee surgery in 2000 when I was 31 (I turn 48 later this year) due to a complete tear of my ACL and partial tears of the MCL and meniscus. After healing I began running, but over time found that to be very hard on my knee so in 2008 I took up road cycling. Due to military deployments I have been an off and on cyclist since then, but find it much, much easier on the knee. I have developed some arthritis in the knee and find after longer rides (3+ hours) I will have some stiffness in the knee, but nothing too bad. I keep my riding to mainly flat, smooth surfaces so I don't have too many issues and will keep riding for as long as I can.