Chain skipping gears happens all the time, and there are many reasons for that. In this case, the chain looks like it moves on the next cog, but it doesn’t. As such, it skips between two gears frequently. Most gear-skipping problems are associated with a derailleur and can be detected during mid-gear shifting. Though there are situations where a bad derailleur adjustment is not the cause of gear skipping but an improper chain line. In such a situation, it would look like the chain only falls out of the larger cogs. It usually happens when you are pedaling backward.