>>1474455ugh.
don't worry about all this autism. for a beginner, think about it like this
front shifter: sets the range, based both on what the terrain is and/or how lazy versus energetic you want to ride.
flat, easy riding, mild hills: middle ring (2)
difficult hill climbs: small ring (1)
for fast riding in the flat or downhill riding: big ring (3)
(it's easy to just look down and see the front gears on the crank, you don't have to use the numbers. they're nice to have but you should really develop a mechanical understanding and also mentally map the position)
rear shifter fine tunes your cadence within the given range. your cadence should favor spinning an easier gear rather than mashing a hard gear. the low numbers are easier and high are harder, but the numbers aren't what you should really focus on, think about which way clicking the shifter makes it easy and which way makes it hard and making a mental map. keep a steady cadence and when it gets too spinny, click to a harder gear. when it feels too mash-y and your cadence starts to slow, shift to an easier gear.
so the "gear" you are in is really a ratio between the rings on the crank in front and the cogs on the rear wheel. related to this is that the easy gears in front are small but the easy rear are big, but the overview is that the easy gears, both front and back, are inboard whereas the harder gears are outboard.
rather than cross-chaining (it will usually make some noise due to strain,) shift the front to the middle gear and re-adjust rear to your cadence.
that's the easiest terms I can put it in. bearing this in mind, probably the best thing to do is ride around somewhere you can be alone and fiddle with all the gear combinations and feel how the different shifts affect your cadence and mentally mapping these hand movements. it's really not very hard, just listen to your body.
