I've been battling pain in my knees for about 6mo. I found it partly is due because of (I hate to say it) poor form while riding. I was putting too much weght on my inside leg while cornering. When i started to relax that leg and use my outside leg more to support myself the pain lessoned. That's partly why I asked about the joint supplements. I did go see a doctor. He ruled out arthritis in me, but said my tendon going over the kneecap was inflamed and was the cause. I get my pain above the kneecaps over the top, and Is worse when i have been siting still (like long rides on the freeway) Icyhot helps me somewhat, but I find using a heat pack is best. Ice seems to tighten me up, and makes the pain worse..
If people don't regulate themselves, others will do it for them.