This is an interesting topic. I bought my first ever HD back in June '13, a '12 RGC with 5000 miles on it. It now has around 8k and have recently noticed every time I ride it, the rear wheel, (chrome CVO extreme chisel wheels) the rear fender, bags, chopped tour pak (when on), shocks etc all have this thick layer of dust covering it. It does NOT appear to be road grime, and don't know how it could be. Seems and looks more like pulverized metal flake dust. No other bike I've owned has done this. I started to wonder if a bearing or something is going out. Have lifted the bike, inspected rear wheel for drag, play, brakes, axle, can't seem to find anything wrong!!! Came across a post about OEM rear brake pads being junk, so my next step is to replace rear pads with Lyndall pads. (I brake with my rear brake 95% of the time with engine/ trans braking and grab for the front when more is needed.) Curious to know if other folks have not experienced this...T