What is a dropped chain?
A dropped chain is when your chain comes off your gears keeping you from pedaling. This can happen in the front chain ring gears or the rear cassette gears. The term "dropped chain" most commonly used to describe the chain falling off the front chain rings (or crank set) on the frame (the inside) or off the big (outside chainring) ring. This leaves you helpless unable to pedal. In most cases this happens when a derailleur is out of adjustment. Usually a slight turn of a limit screw located on your derailleur will fix this problem.