Originally Posted by
Homebrew01
I generally shift 1 at a time, harder or easier as terrain changes.
The front chainrings are like "High" and "Low" range.
Lots of short hills near me, so I am in the small chainring most of the time.
i shift to the large ring if I have extended time on flat roads or longer downhills.
I have no idea which gears overlap, not really relevant when riding.
Whichever gear keeps my RPM in the 85 - 95 range
That's really all there is to it. You figure out what cadence and load you're comfortable at and just change up or down to keep yourself there. Occasionally look down to make sure you're not cross-chaining, but mostly it gets noisy when you do, so you'll find yourself looking down anyway.
Over time, you'll get a feeling for how far to go up or down when the grade changes, so you'll shift into bigger gears (meaning smaller cogs) as you summit, or shift into smaller gears (meaning bigger cogs) as you lose momentum going up a hill. You'll also figure out how many cogs you need to go up or down when you change from one chainring to another in the front. Some of my bikes, with 53/39, it's two. The 50/34 and 52/36, it's 3.
The key is not overthinking. I generally couldn't tell you what gear I'm in, till I'm in either the largest or smallest and can't go any further.