“Granny gear” is the simplest gear to use on the bike: it has the smallest front ring and largest rear cog. It makes you pedal less hard when you climb very steep hills.
Cyclists use granny gear on an inclined hill. It allows them to pedal quicker despite moving at a slow pace. It is less stressful on their muscles and allows them to continue climbing the hill. It makes them slower but enables them to reach the top of the hill instead of stopping. It is common in road cycling, gravel cycling, and mountain bike gear.
