Originally Posted by cyccommute

Again, the limit screws only limit how far the derailer moves but not how it moves. Chain rubbing in extreme gears…like the biggest cog on the rear with the large chainring…is somewhat normal. It can be a function of the derailer or the derailer alignment but even then, you are more likely to experience chain rub in those combinations. If you are using Shimano front derailers, the more expensive ones tend to rub more in my experience. Those tend to be narrower than cheaper versions (Tiagra and lower).

Your shifters should also have a “trim” feature which is a soft click (like about a half shift) in the shifter. This will move the front derailer just a little bit in those more extreme gears and reduce rub. I use triples exclusively and the trim is in the middle ring. I don’t recall if it is on the inner ring or outer ring on doubles.

Finally, you don’t need to use the large ring/large(r) cog combinations. Use a gear calculator and see where those gears are duplicated. Shift before you get to the gears that tend to rub.