Would 4 mm really make that much difference in chainline on a derailleur bike? On a non-derailleur bike, sure.
To me your original description sounds like you're just cross chaining and in that case the sound is perfectly normal. It's your bike's way of saying, "stop doing that, I don't like it." But then I don't know what I'm talking about most of the time.
Originally Posted by
GordoTrek
everytime i adjust my front derailleur i get chain noise/rub on the outer part of the derailleur,when its on the big cog in the front and into the new 8sp cog in the back
i can't get it perfect, its a shimano slx triple front
You don't want to ride in the big ring in front and the big cog in the back (or the small ring in front and the small cog in back. That's just bad news. Hard on your chain and gear teeth.