Remember when you did not think about the gears on your bike? Your bike had a bike sprocket connected to the pedals and a small sprocket connected to the back wheel an that's all you needed. Then you got a little older and got your first 10-speed. That bike had two sprockets up front and five on the back. In all likelihood, the shifters were a pair of levers connected to your bike frame near the handlebars. As time went on the shifters moved to the handlebars themselves and then became advanced-looking dials right around the grips. And next thing you knew, instead of a paltry ten speeds on your bike, you were riding a 27-speed mountain climbing machine!
Why all these gears? To make riding faster and easier, of course. Whatever the number of gears your bike has, if it has 2 or more then there's a basic set-up which almost every bike employs.
First of all you have your front and rear sprockets. These, along with the chain, form the most basic components of the geared system. To determine your gear ratio you compare the number of teeth on the front sprocket to the number of teeth on the rear sprocket.
If your front sprocket has 52 teeth, and your rear sprocket has 20 teeth, then you're looking at a ratio of 2.6. The higher the ratio the faster the gear. Typically the gears on the front, starting from the inside, get larger as you move out. On the back wheel, though, the largest gear is typically the farthest inside and they get smaller as you move out.
The next key component for your mountain bikes gears is the derailleur, or derailer. The derailleur is what moves the bicycle chain from gear to gear. A typical shifting system employs both a front and rear derailleur. Without the derailleur you would not be able to shift gears. The derailleur consists of pulleys and the cage, which is the part which actually comes into contact with the chain. The pulleys are attached to the gear cables. There are separate cables for the front and rear derailleurs. The gear cables connect to the gear shifters.
There are a variety of gear shifters available today and they cover a wide price range. The gear shifter is what allows you to change gears. The first type of shifters were levers known as friction shifters. These worked simply by pulling the cables attached to the derailleurs.
Friction shifters can be troubling because the way they're designed you can easily get caught between gears and accidentally damage your gears or even wreck. The more advanced variety of shifter is known as the index shifter.
Index shifters have specific stopping points and are calibrated to perfectly shift from gear to gear. They remedy the drawbacks of the older friction shifters. Gear shifters may be placed anywhere from the frame to the handlebar base to the grips to models which seem to be part of the brake levers.
Mountain bikes have multiple gears to make it easier for you to negotiate difficult terrain. Higher gears are there to help you speed downhill or across the flats, and lower gears are there to help you surmount those difficult inclines. Remember, it's best to shift gears when you're not putting a lot of stress on your pedals. Shifting when there's heavy pressure on the pedals can damage your shifting system.
Source by Gregg Hall