Fortunately for all our LBS's there are still people that need to pay to have their flats and other minor things fixed. They no doubt account for a good portion of repair shop business.

I'm a bit ashamed to admit that I don't know much about adjusting derailleurs/shifters, changing cassettes or really anything to do with geared bikes. I'm working on it, but I've only been working on ss/fg bikes since I started doing repairs myself.