Originally Posted by HTupolev

Backwards. High gears are the ones you tend to use when going faster, low gears when going slower.

It's called "higher" because the ratio of rear wheel rotations per crank rotation is higher.

If you're on a 44-tooth chainring up front and an 11-tooth cog in back, the ratio is 44/11 = 4. So when pedaling, every time you turn the cranks in a full circle, the rear wheel will spin 4 times.
If you then downshift to a 22-tooth cog in back, the ratio becomes 44/22 = 2. So the rear wheel now spins twice every time you turn the cranks once: a much lower gear,


People mostly don't number their gears like this, because gear ratio counting doesn't convey much information to other cyclists. Two different drivetrains will have wildly different meanings for what "gear 13" is.

The highest gear on my Emonda is when I'm in my 50-tooth chainring up front and 11-tooth cog in back. I call it my highest gear, or I refer to it as fifty-eleven, or some other descriptive term.