Lets be clear, This is NOT a tutorial. You don’t NEED another tutorial, you don’t WANT another tutorial.
I’ve recently acquired a pair of bicycles for my wife and I. They came fully assembled, but the boobs who threw them together at the store didn’t know much about bikes, so pretty much everything has needed adjustment. First I had to adjust the derailleurs, the things that make the gears shift. Doing this is easy, there are guides all over YouTube. I watched several, then I just did it. took about fifteen minutes and required flipping my bike upside down. Then the brakes were too loose. I had to tighten them up. Loosen a bolt, squeeze the calipers together, tighten the bolt again. Quick and easy. Well, then I had to replace the “Twist shifters” with something that didn’t break regularly. I bought some beautiful Shimano shifters on Amazon, and the installation was very simple. I just mounted them to the handle bars and ran the cable, then readjusted the derailleurs as before. This most recent piece was a bit of a chore though.
I got new bike seats. Look at the bottom of your bike seat, it’s probably got two metal rods with some sort of kerjigger between them, all held together with bolts. The idea is simple: Loosen the bolts, swap the pieces, tighten the bolts. In practice, getting in to the bolts was nigh on impossible, and I didn’t own any wrenches the right size. I had to use a pair of pairs of pliers. It was still really easy.
All around, bikes are VERY easy to maintain and service and adjust and repair and.. well, you get the idea. I haven’t found a routine maintenance or simple upgrade task that can’t be done by YOU, the rider, after watching a YouTube video, or even more easily, by simply examining the parts to see how they fasten. Don’t pay the guys at the bicycle store for the easy stuff, grab a wrench and a screw driver, and achieve some independence!