It was in the first mile of a metric century. At the bottom of a hill were RR tracks for which we had to slow. We started to climb immediately after the tracks, and it was apparent I was in the wrong gear. While this was totally my fault, my stoker didn't have her "head in the game" so early in the ride. I was in the big ring,and i ran out of gears on my cassette quickly as we lost whatever momentum we had. I tried to get into the middle ring, but nothing was happening as we were under load. All I got was a click click click from the front derailleur. The next thing I knew, the chain was off and down we went on our left side. Our elbows were scraped and my ego was bruised but otherwise we were fine. I had this weird soft tissue pain in my left hamstring that felt like a cramp or a sprain that bothered me until the first break. I took some Endurolytes and that seemed to help. We finished strong. We were arguing whether this qualified as an actual crash because it was so lame and stupid. When I got home, I felt this big welt on my left butt cheek that I hadn't noticed before. I could not figure out where it came from until I realized I must have landed on the end of my stoker's handlebar (she doesn't have drop handlebars). This welt is pretty impressive and now it's turning lots of different colors. I began to wonder if that weird pain I felt in my hamstring was related to this near impalement. I'm thinking it might have been referred pain or perhaps some superficial trauma to the sciatic nerve. The pain is completely gone now. Lesson learned; pick the right gear and don't try to change rings under load.