I bought a 2019 Tarmac Disc Expert last year right around this time. Since then, I have put around 6000 kms on it, about 2500 of which were on an indoor direct-drive smart trainer. I never ride in the rain, I only weight about 65 kg, I tend to favor cadences at 90+ rpm, and I take pretty good care of my bike.
Some of my riding buddies have told me that it’s time to replace the chain because it has a lot of kms on it. However, I recently used a chain wear indicator to measure my chain, and it measures to be almost brand new. I even used the same wear indicator on a brand new bike, right out of the box, same Ultegra drivetrain, and it falls pretty much in the exact same place as it does on my bike. For the reasons mentioned above, I can see why I get more life out of a chain than a typical rider, but I still have no idea how it has lasted this long.
My question is: should I replace the chain or should I keep the current one, and since I have waited this long should I also replace the cassette? While the chain may show hardly any sign of longitudinal wear, I am aware that it can also wear laterally (the chain and rollers gets sloppy side to side but not stretched), which is a bit harder to spot. I have had no shifting issues whatsoever. The only thing I have noticed is that the chain is occasionally squeaky, and lately I’ve had to use quite a lot of lube to get rid of the noise. I’m thinking of just replacing the chain and holding off on the cassette for now, but I’d like to know people’s thoughts. Thanks in advance.