Taking SCARY out of used bikes, one bike at a time.
Yes, it is. It’s from a lot of riding or how often you change those gears. The chain will stretch over time if your grind underload those gears like downshift and crank. If you shift a lot and keep a faster cadence, sometimes that will lengthen the life of the chain.
When a chain stretches, it changes the spacing on your cassette. So the idea is to change the chain out before the cassette is compromised. To keep your drive-train smooth and not damage parts. Change your chain at .5 stretch and switch out your cassette after two chain replacements.
Suppose you don’t have a chain checker tool (and who does, only bike tech). You can use a standard ruler and match pins to inches. Over 12 inches, it should be close, but if it’s off, the chain is most likely stretched, and time to replace it.