Im riding an 05 Iron Horse that has a Shimano Alivo system on it....I know its not a great derailer but Im savinf my money for a full set of XTR's. Anyway my gears are shifting really good but when Im in 2,7 or 2,8 I get a little chain clatter when I crank hard. It looks like my chain is rubbing on the derailer. Is this something I can adjust out with HI LO screws or do I have to change my tension all together?