In the summer of 2016, I started out on my dream tour from Portland, OR to Savannah. 14 months earlier I had complete knee replacement surgery on my right knee. After a year of rehap and exercise, it appeared to be good as new. I'd skied on it that winter, biked a couple of centuries and had the OK form the doc. Long story short, after biking fro Portland to SF and across the Sierras via Yosemite, things were great. Then at about 2000 miles, in the middle of the Nevada desert, my knee began to give me excruciating pain to the point I couldn't stand it. I ended up having to abort the trip and taking a bus home. Terribly disappointing. At home, I went back to my surgeon and told him my sad story, After he examined me and x-rayed the knee, he could find no obvious problems and concluded that I had just pushed myself and my knee too much. I was doing 80-80 miles a day in Nevada over numerous mountain passes (Nevada is not flat) with a fully loaded touring bike. Since then I have recovered totally, I think, and have had no problems with the knee at all. That's my story. I'm currently 69 and if things fall into place, plan on taking a cross country tour again this summer from Portland to Savannah but I'm staying out of fricking Nevada, thank you very much.