Anti-drop device of bicycle chain

Bicycles that people use, in particular to constant-speed bicycles, generally have a defect that chains of the bicycles are easy to drop. Because the chains can get abraded, loosened and lengthened after the bicycles are used for a long time, the chains are easy to drop when getting lengthened and loosened. The utility model provides an anti-drop device of a bicycle chain, which comprises a fixed link, a fixed plate, a spring rotating shaft, a gear, a gear carrier and a bolt, wherein the fixed link is provided with a perforated slot; the gear carrier is provided with a locating pin; the gear is arranged on the gear carrier; and the gear carrier is rotatablely connected with the fixed link through the spring rotating shaft. After the anti-drop device is arranged on the bicycle, the chain can be effectively prevented from dropping, accordingly, the normal use of the bicycle is ensured. A finished product is a completely independent device, has a simple structure, low cost and a obvious effect, is easy to proces