Every person who considers themselves a cycling enthusiast should know how to do at least some basic bike repairs. This is not just to satisfy an unwritten standard of being a bikehead, but because it has a lot of practical implications as well. It can make the difference between dealing with a minor issue quickly on your own or waiting a couple of days for a busy mechanic to squeeze you in. Moreover, in the long run, doing the dirty work yourself will save you a lot of money.
Man, if you're starting out and you know you'll need several components for a bag... just get this. It will save you so much time picking everything out that even if you balk at the price (amazing value, by the way) I bet that if you did the math using your hourly wage and the time spent picking everything out and making sure it fits... you'd save a lot of money and a lot of irritation if you just got this. Just get this.
Friction gear systems are a lot simpler to adjust, because the movement of the derailer cable can be modulated as you ride, every time you change the gear- they require less cycle maintenance. Modern index shifting systems are a little more complicated because each ‘click’ must release the exact right amount of cable to allow the derailer to move the correct distance to move the chain from one gear to another. Setting up and adjusting a derailer is not difficult and requires only basic tools, but there is a methodical procedure to follow.