A Question about cassette wear

[NotAveJoe]

What causes more wear to the cassette --

Being in the wrong gear for the terrain (with a too-slow cadence, probably), or;
Shifting under tension?

Or maybe something else?

 

[steve_sordy]

A worn chain does more damage to a cassette than anything else. The damage is not instant, but is constantly wearing away the tooth faces, because the chain roller is sliding up and down the tooth face instead of just sitting there. Mostly you won't notice until you fit a new chain only to find that the new chain will not run smoothly on the old cassette. Instead, it skips under pressure and won't shift smoothly. Best then to put the old chain back on and run the chain/cassette combo into the ground.

The other things you mention are also not good. Poor shifting, especially under load is bad for the chain. But it is easily avoided and once you learn the skill, you will become psychologically incapable of doing it (well it was for me).

 

[BeBiker]

...you won't notice until you fit a new chain only to find that the new chain will not run smoothly on the old cassette. Instead, it skips under pressure and won't shift smoothly. Best then to put the old chain back on and run the chain/cassette combo into the ground.

Exactly the situation I'm in with my E-st900 actually.