On my 20 mile bike ride yesterday, we were at about mile 16, climbing a nasty hill, when I went to down shift. The front derailler wouldn't go, so I tried again. Still no go. I started fiddling with my rear derailler in order to get the front one to go. I switch the front one, one more time, and the chain popped off. Of course, at this point, I'm doing about 3mph. I realize I'm very screwed about this point, as my feat are clipped into the peddles. I start spinning my feet wildly, trying to keep from falling over, when I realize that my chain isn't attached, and peddling won't help me. I try to unclip, but realize that without the bike in motion, I'm doomed. I start yelling, "Crap, crap, crap, crap!" as I try to figure out how to fall over without damaging the bike, or me. I teeter to the right and fall over. I scraped my elbow a bit, but since I wasn't moving, there was no road rash. I managed to scrape my rear derailler though, so shifting is a little wonky. I need to fix that, but I wasn't motivated last night. So, I'm ok, but it's not something I want to do anytime again.