The chains stretch over time, and teeth of the cassette get worn. The more you ride the quicker this happens. If you take it to a shop, they can quickly measure

The chains stretch over time, and teeth of the cassette get worn. The more you ride the quicker this happens. If you take it to a shop, they can quickly measure the chain to make sure you're good. Chains are pretty common to replace and shouldn't be too expensive. Cassettes as well, they're often changed at the same time as the chain. Otherwise, regular cleaning and lubing will help extend the life.