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Feb
08
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Mountain bikes today are equipped by as many as 27 gear ratios. It is a combination of three different sized sprockets in front and nine in the back to produce gear rations.
This design is to allow the rider to crank the pedal at a constant speed no matter what kind of slope the bike is on. You could understand this better by picturing a bike with a single gear. Everytime you rotate the pedal one turn, the rear wheel would rotate one turn as well (1:1 gear ratio).
If the size of the rear wheel is 26 inches in diameter with 1:1 gear ratio, in one full turn of the pedal could cover 81.6 inches of the ground. It means that you are pedaling at a speed of 50 RPM and that the bike can cover over 340 feet per minute. The equivalent of this is the walking speed or 3.8 Mph. This may be an advantage for climbing a steep hill but might be a disadvantage for ground or going downhill.
If you want to go faster you need a different ratio. In going downhill at 25 MPH with a 50 RPM cadence at the pedal, you will need a 5.6:1 gear ratio. Having a lot of gears in your bike gives you a large number of augmentation between a 1:1 gear ratio and 6.5:1 gear ratio so that you can pedal at 50 RPM no matter how fast you are going.
In a normal 27 speed mountain bike, there six gears that are so close to each other and you can not notice any difference between them.
Most bike rider chooses a front sprocket suitable for the slope they are riding and stick with it even it is difficult to shift under heavy load. It is more easier to shift the gears on the rear.
It is best to choose the smallest sprocket on the front then shift between the nine gear on the rear when you are climbing on a hill. The more speed you have on the rear sprocket, the more advantage you will have.
It is very important in a mountain bike to have gears. They dictate your overall speed and without the gears you will not be able to build speed nor you will not be able to pound the pedals. Gears are install to help you move the pedals and help you build up speed.
There are a lot of gears available for a mountain bike. All of this will help you build up a lot of momentum if you use the properly.