>>1399305Chain skipping = worn out teeth on gears (back gears more commonly). Look for teeth that are fin-shaped instead of being symmetric and square.
Shouldn't be super expensive to replace ($50-$100 depending on parts), and you'll probably want a shop to do it instead of trying to DIY it because it takes some special tools. You'll need a new chain too whenever you replace the gears. It's something that wears out and needs to be replaced on any bike every so often.
