I have a Schwinn Fastback that uses a triple crankset. When my chain is using the largest rear cog, it rubs against the left side of the front derailleur making for an annoying noise when I pedal. This happens when I'm using the small or middle front chainring. Of course, I don't use large to large simultaneously so there's no cross issue. I'm not having shifting problems, per se, but is there a way to adjust the front derailleur so that my chain doesn't rub against the derailleur when I'm using the largest rear cog?