For a while I've known that my rear shift cable was too loose on my 9-speed Shimergo setup. I was actually using the 2nd through 10th shifts, and I had the cable adjuster all the way tight. There was no problem with this until I changed the cassette from 12-27 to a much larger 11-34 and a longer chain, then it started ghost shifting. I stopped about halfway through my ride and took out the cable slack at the pinch bolt. Now I'm using 11th thru 3rd and it's much better. Other than that, took it easy.