RC Cars, Collectible Model Train
Sets, Collectible Model Cars & More
How Mountain Bike Gears Work
The gears in mountain bikes just keep getting more and more
intricate. The bikes of today have as many as 27 gear ratios. A
mountain bike will use a combination of three different sized
sprockets in front and nine in the back to produce gear ratios.
The idea behind all these gears is to allow the rider to crank
the pedals at a constant pace no matter what kind of slope the
bike is on. You can understand this better by picturing a bike
with just a single gear. Each time you rotate the pedals one
turn, the rear wheel would rotate one turn as well (1:1 gear
ratio).
If the rear wheel is 26 inches in diameter, then with 1:1
gearing, one full twist on the pedals
would result in the wheel covering 81.6 inches of ground. If you
are pedaling at a speed of 50 RPM, this means 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 ideal for
climbing a steep hill, although bad for ground or going
downhill.
To go faster you'll need a different ratio. To ride downhill at
25 MPH with a 50 RPM cadence at the pedals, you'll need a 5.6:1
gear ratio. A bike with a lot of gears will give you a large
number of increments between a 1:1 gear ratio and a 6.5:1 gear
ratio so that you can always pedal at 50 RPM, no matter how fast
you are actually going.
On a normal 27 speed mountain bike, six of the gear ratios are
so close to each other that you can't notice any difference
between them.
With actual use, bike riders tend to choose a front sprocket
suitable for the slope they are riding on and stick with it,
although the front sprocket can be difficult to shift under
heavy load. It's much easier to shit between the gears on the
rear.
If you are cranking up a hill, it's best to choose the smallest
sprocket on the front then shift between the nine gears
available on the rear. The more speeds you have on the back
sprocket, the bigger advantage you'll have.
All in all, gears are very important to mountain bikes as they
dictate your overall speed. Without gears you wouldn't 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 types of gears available in mountain bikes, all of
which will help you build up a lot of momentum if you use them
the right way.