I replace my 11 speed chain when it's showing as worn by measurement. I replace the cogs and rings when they are showing as worn because of the way they act. Primarily when a new chain slips on them.

Looks of the teeth on the chainring and rear cogs can be deceiving on bikes that are from this century and slightly into the previous century.


If you don't replace your chain soon enough then it wears the cogs and rings faster. If you have worn out cogs and rings that aren't causing your chain to slip, then I suppose they'll wear the chain faster.

As with most things, you have to decide whether you are better served doing pre-emptive replacement of stuff to try and save the wear on something else or just wait and replace when things aren't working together at all.