cyccommute 

I don’t understand why people have so many problems with front derailers. They work the same way as rear ones. There’s a bit more in terms of adjustment and movement than the rear but not too much. The gap above the chainrings does have to be 2 to 3 mm above chainrings (I use a nickel to set the gap). This is the “B screw” of the front derailer. The outer plate of the derailer needs to be parallel to the outer chainring (save that little plastic block that comes with the derailer).

For limit screws, set the lower one so that the chain just clears the derailer’s inner plate when the rear is in the lowest gear. For the high limit, set it so that the chain just clears the outer plate. Don’t make the cable too tight or the chain will rub on the inner plate in the low gear. Also don’t make it too loose or the derailer will rub the outer plate. It needs to be just right

Chain line has to be considered but that’s only an issue if you are changing the crank set. For example, I’ve put mountain bike cranks on road bikes. That requires some moving of the chainline...usually inboard...to get it to shift. But even when I have to messing around with the chainline, I can still tune the front so that shifts flawlessly.