Generally, I don't have sore knees from biking, but there were problems when I was a runner. I feel pretty lucky that I'm not having a great deal of problems with my knees, but I'm wary of dishing out too much abuse and paying for it later. There are some hills that I can seek out, and I knew I would see those words-"hill repeat" Ugh! Yes I know, I'll be stronger for doing them.