The gears in mountain bicycles just keep getting more complex. The bikes of today have as many as 27 gear proportions. An off-road bike will use a
Combination of 3 different sized sprockets in front and nine in the back to supply gear proportions.
The basic concept behind all of these gears is to permit the rider to crank the pedals at a continuous pace regardless of what sort of slope the bike is on. You can understand this better by picturing a bike with simply a single gear. Whenever you revolve the pedals one turn, the rear wheel would revolve one turn as well ( eleven gear proportion ).
If the rear wheel is 26 inches across, then with eleven gearing, one full twist on the pedals would lead to the wheel covering 81.6 inches of ground. If you are pedaling at a speed of 50 Revs per minute, this indicates that the bike can cover over 340 feet of ground per minute. This is only 3.8 Mph, which is the equivalence of walking speed. This is excellent for climbing a steep hill, though bad for ground or slipping downhill.
To go quicker you’ll need a different proportion. To ride downhill at twenty-five Mph with a 50 Revs per minute cadence at the pedals, you’ll need a 5.6:1 gear proportion. A bike with a lot of gears will give you a sizeable number of increments between a 11 gear proportion and a 6.5:1 gear proportion so you can always pedal at fifty R.p.m, regardless of how fast you’re really going.
On a normal twenty-seven speed mountain bike, 6 of the gear proportions are so close to one another that you can not notice any difference between them.
With actual use, bikers tend to choose a front sprocket acceptable for the slope they’re riding on and keep it going, though the front sprocket can be tricky to shift under heavy load. It’s way easier to shit between the gears on the rear.
If you’re cranking up a hill, it is best to choose the smallest sprocket on the front then shift between the 9 gears available on the rear. The more speeds you have on the back sprocket, the bigger advantage you will have.
All in all, gears are very important to mountain bicycles as they dictate your overall speed. Without gears you would not be able to build speed nor would you be able to pound pedals. The gears will move the pedals and help you build up speed.
There are all sorts of gears available in mountain bikes, all of which will help you put up a lot of momentum if you use them the right way.