How to seriously get dropped: You're on a large group training ride for local racers, and your (in this case, my) chain falls off the outer chainring, and you're unable to coax it back on with a few pedal strokes. Make sure it happens just as the group splits off into A, B and C groups and all cylinders are firing. It only took 30 seconds to stop and fix the chain, but by the time I got rolling again, all riders were out of sight. I didn't exactly know the turns, and didn't feel like being lost, so I ended up doing a solo 20 miles to the regroup location.