I have my Ultegra triple FD adjusted perfectly except for a slight chain rub in the biggest ring and the smallest cog. It is not a cable adjustment. I believe I have to adjust the limit. In order to move the outer plate 0.5-1.0mm. away from the chain, I believe I have to turn the high limit screw CCW. How far can I un-loosen this screw? You can't back it out entirely, can you? I assume you can only adjust it so far and then it stops, right?