My knees have bothered me now and then since I was 20 years old. I put up with it forever. My knees always hurt climbing or descending stairs. I could tell when i overdid it the previous day if coming down stairs in the morning hurt more than usual. 10 years or so ago, my wife went whole-foods-plant-based (vegan) to successfully deal with some health issues and I gradually joined her. Guess What!? I have been coming down the stairs each morning for the last several years without pain. I am not easy on my knees, had a couple meniscus repairs, bowlegged, pronate, flat footed. My understanding is that animal products cause inflammation.
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I don't do: disks, tubeless, e-shifting, or bead head nymphs.