Mountain Bike Deals

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Available until 25th October 2009

Today's Mountain Bikes ften come with as many as 27 gear ratios. Even a 10-speed of previous years seemed like a lot. Isn't this overkill? Not necessarily. To find out why, let's consider how gears work and from that you should then understand the importance of Mountain Bike gears.

If there were no multiple sprockets and derailleurs the chain would just wrap around a single rear wheel sprocket. That would fix a single 1:1 gear ratio. In other words, the wheel would spin no faster or slower than you could pedal it.

Mathematically, it works out that a standard 26" wheel would then travel about 82 inches (208 cm) in one revolution. Pedaling 50 revolutions per minute would push you forward about 340 feet in one minute. That's less than 4 miles per hour (6 kph). Pretty slow for anything but uphill conditions.

How You Benefit

Having more Mountain Bike gears allows you to go faster with the same number of revolutions pumped by your legs. At the same time, additional gear ratios allow you to do that without exerting excess effort. It smooths out the force needed over varying terrain and conditions.

Hills, bumps, and more require you to push harder. Sometimes that's exactly what you want. But if you want to maintain the same force and still get speed, extra gear ratios are a must. Effective Mountain Bike gears allow you to maintain the required force to handle hilly terrain.

One of the basic mechanisms that makes that possible is the derailleur. These are small metal devices that allow the bike to shift smoothly from one sprocket size to another.

The sprocket size is related to the gear ratio, and so to the amount of force needed to maintain a certain speed. Smaller sprockets are easier to turn. But, that tiny sprocket has to be turned through more revolutions to make the same distance.

Balancing those two factors makes it possible to move uphill more easily and still maintain a reasonable speed. On a level surface, a larger sprocket requires only moderate force and let's you go faster.

At the same time, the rear derailleur has to keep the chain tense in order to avoid having it fall off the sprocket. That's just another of the ways in which these little mechanisms are so clever.

Modern Exception

There is a current exception to all this complexity, though: the singlespeed mountain bike.

A singlespeed has only one gear ratio, but still allows coasting. It seems very limiting, but it have two good purposes: low weight and simplicity.

The nine rear sprockets and three front ones (plus cables and more) on a standard bike add a fair amount of weight. At the same time, because they are more complex, there is more to maintain and more to go wrong. A singlespeed reduces the weight to a minimum and lowers the need for maintenance and the possibility of failure.

Singlespeeds are set according the rider's ability and experience. But for those looking for an alternative, they're worth considering.

To decide whether you prefer a singlespeed or 27 gears, consider the type of riding you plan to do and your abililty. Unless you have easy terrain, a singlespeed takes considerable effort.

So know you know why gears are important and particularly why mountain bike gears provide a better riding experience.