yes
well from my experience "if understand the question correctly" take the number of gears on the back derailleur and multiply that number with how many gears are on the front derailleur
It depends on the bike if the engine of bike is heavy it has more gears. Usually 5 gears are max gears.
That depends on the riding conditions. Having more gears to choose from means that a rider can find the best gear for more types of riding conditions. But if the riding conditions (degrees of slope to climb/descend etc) don't change much, then a rider won't use that many different gears. And the gears a rider isn't using isn't any benefit. The fastest bikes on level ground are usually track bikes, and they only have one gear.
2 gears
MotoGP bikes have 6 gears.
depends on the model. from 2-7 gears
Depending on the bike yes most adult sized bikes have gears
if you don't keep your chain and gears on your bike greased it will rust and come off.
Depending on the mountain bike that you have will depict the amount of gears. Most bikes for adults typically have about 21 gears. If this does no answer your question then what are levels?
Changing Gears Flagstaff and the Mountain Bike - 2011 was released on: USA: September 2011
To change gears on the bike, all you have to do (while riding it) is press the B button. You don't have to hold it in, either. ~Lucario
a track bike, or a bike with internal hub gears.