When should I be replacing it? Looks pretty good at 19k miles.
When you can't get the tension right as you have run out of adjustment marks on the tension block. There may be a more technical defnition such as the length of x number of links, but no idea what that would be.When should I be replacing it? Looks pretty good at 19k miles.
i would always recomend replacing sprockets with a worn chain, or you will soon have two worn chains
Great points, but... I ride my bikes A LOT, (27 years? maybe 200K +-) and I've never had a chain reach over 20K regardless of maintenance (maybe 12K, and I'm pretty sure it's not because of my incredible watts, because I'm a fairly lightweight and not a sprinter). My rule of thumb is a new cassette every two chains. It isn't just the chain that wears, the rear cogs wear too independent of the chain from shifting, chain engagement angle, even the slightest chain stretch, etc....For a data point, my road bicycle is 27 years old, has 89,000 miles on it and is only on its third chain (I keep my chains well lubed, which effectively prevents wear inside the links, which effectively prevents chain "stretch"). None of its sprockets have never needed replacing, because I've never ridden with a stretched chain.
That's when it needs changing. Or, do as my Bandit did, change when it starts to jump teeth on the countershaft sprocket. Doh! I think that was the heat treat being bad. My story, sticking to it.kink up and bind up with the tight spot.