I have a real simple RD adjustment question that I am struggling on how to describe. I just swapped out my Shimano 105 RD for an Ultegra 6700 RD. I have noticed sometimes that when I shift to a bigger cog on the cassette I get chain rub noise. If I hit the shifter slightly (as if I wanted to shift down to the nest smaller cog) the noise goes away w/o any shifting taking place. Hopefully I described this correctly and a light bulb went off. I experienced this time to time with my 105 RD but am starting to experience this more over the past few weeks with my 6700 RD to the point it is almost coming routine. I assume this is cable tension. Should I tighten or loose the cable with the rear barrel nut? Yes, to answer your question I have never wrenched on my bike until now.