Hi
I have a type of arthritis brought on by crohn's disease, called crohn's arthritis (duh).
It's not degenerative like osteo or rheumatoid, but gives me nice joint pains in my hips and knees if the disease is active. I also have "bad knees" (thanks dad). I had knee surgery on my left knee at 14, and expect my right one to go out in a few years if I'm on his schedule - I'm 30.
For the most part, cycling is fine on my knees. Running is out of the question, at least any long distances. I notice that my joints start to hurt after about 30-40 miles on the bike. I'm fine on shorter rides. I don't really know why, but I do know if I pop a celebrex before a longer ride this doesn't happen. Since I'm only taking 1 pill as needed, I don't really worry about all the warnings with celebrex, since those problems occur at higher, maintenance doses.
Hope that helps
"Only the meek get pinched, the bold survive"