>>2015764>Can it be that the gear shifter is what's faulty and not the derailleur?No. Shifters can gum up and stop shifting easily, but that won't mess up your indexing.
What is usually the cause of 'can't tune indexing' is excessive friction in the housing, which causes clutching, so like the inner cable goes out a bit, and doesn't go back when you shift back because the friction is too high.
Short of recabling (definately a good idea) you can unbolt the inner, don't pull the housing off the end of the inner, because you'll never get it back on past the crimped part, but that allows you to pull the pieces of housing out of their stops, and slide them around, working oil into them. That usually fixes stiff housing, unless the ends/ ferrules are really disintegrating.
Beyond that
>>2015776>It can if the hanger is bent.That's the other thing that causes 'can't tune indexing'. And it's easy to fix. You can eyeball it, unbolt the derailer, and simply bend the hanger straight with a big crescent wrench. There's a proper tool for it which can do it more accurately, but for 9 and lower spd systems it's good enough.
The derailer itself can be bent too.
>Can a derailleur be fucked beyond adjustment or am I doing something wrong?So yes, it's possible that your derailer is bent, sometimes this is impossible to tell, and it will just never index correctly. That's really at the end of the line, and fits the general last strategy which is just if you can't setup your shit, change the parts. It's pretty rare though, unless someone (maybe you) has tried to bend the hanger with the derailer.
