I'm quite new to cycling, a student riding a used hybrid bike for budget reasons. I got two punctures (my first since i started riding) last week, and in the process learned how to change inner tubes myself. After changing the tubes and putting my wheels back on i struggled for hours trying to align the brake discs on both wheels. A few frustrating evenings (first with changing the tires, then with aligning the wheels) later, i managed to get my back wheel aligned. However, the front disc was still grating against the brake, no matter what i tried. I finally had enough and went to my local bike shop to ask where I'm screwing up. I told the owner I was trying to learn to fix some basic things myself, but was feeling stuck. From the moment I walked in he looked at me like I was stupid. He took a quick look and tightened the bolts holding the wheel.…