Mountain Bike Gear Shifting System Components
This is to give you an idea on what happens technically if you shift gear. If you understand how the gear works, shifting gear will be something that comes natural instead of a thing that you should memorize.
The crank which is bolted onto the consists of three chainrings.
Rings are bolted into the cranks. They come in three size ranges. The big ring (48-42 teeth), the middle ring (36-32 teeth), and the small or "granny ring" (26-20 teeth).
The "sprockets" or "cogs" are found in the rear hub.
Modern sprockets consist of 7-9 size ranges from 36-11 teeth. Normally, the 7 & 9 speed sprockets have the same heavy and light gear.
The difference is in the mid-range gear. The 9-speed sprocket has more mid-range speed which lessens the change in speed upon up or down shift.