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Mountain Bike Gears: What Are They Good For?

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Mountain Bike Gears: What Are They Good For?

The joy of the mountain bike is that they come with so many gears that, if you shift into the lowest one, you can ride up a mountain with no problem. It may take you all day, but you can do it.

Generally, mountain bikes have lots of low gears so you can climb steep hills more easily, road bikes have more higher gears to boost top-end speed. A growing number of bikes now have simpler 1X drivetrains, meaning they have only a single front chainring.

It’s been a long time since the “10-speed” bike was the ne plus ultra of biking sophistication when it came to gears. These days, especially in mountain bikes, you can get anything up to 27 speeds.

What are all these gears in aid of? Quite simply, they allow you to pedal at the same cadence – regardless of whether you’re going uphill, downhill, or cross country.

Broadly speaking, mountain bikes have lots of low gears so you can climb steep hills more easily, while road bikes have more higher gears to boost top-end speed. More gears means more choices, but also more complexity for riders (and shop techs). At the other end of the spectrum, a growing number of bikes now have simpler 1X drivetrains, meaning they have only a single front chainring.

However, the main reason why mountain bikes have so many gears is to assist you in climbing up those mountains!

The main thing to remember when shifting is that you must always shift while pedaling, otherwise you’ll strip the gears.

Most of the bikes on the market today have external drivetrains, which have been refined into simple, lightweight and efficient systems.

Gears are changed on the cassette (a set of sprockets on the rear wheel) by the rear derailleur. This shifts the chain up or down the cassette. As the derailleur moves to change gear it forces the chain against ramps or steps, moving it onto a bigger or smaller sprocket.

Parts of the Bike Drivetrain

On a conventional multi-speed bike, the drivetrain includes the following components:

Crankset: The component your pedals are attached to has several parts, with chainrings (sprockets) being a key component in shifting. Bikes have one, two or three front chainrings (gears).

Cassette: Your bike’s rear cassette is the stack of cogs (gears) mounted on the right-hand side of your rear wheel.

Chain: The chain connects the front chainrings and the rear cogs, so that when you turn the pedals you also turn the wheels. The number of teeth on the cog and chainring combine to determine how easy or hard it is to pedal.

Derailleur: This is the mechanism that physically guides the chain from cog to cog or chainring to chainring when you shift gears. Most bikes will have a rear derailleur, whereas not all bikes will have a front derailleur.

Shifters: These controls, whether levers, twist grips or integrated with brake levers, operate the derailleurs via cables (or circuitry in electronic shifters). On most bikes the right-hand shifter controls the rear derailleur and the left-hand shifter controls the front derailleur.

Drivetrains with Hub Shifters

There is a growing number of bikes that are using an internal-gear hub, which typically eliminates the need for derailleurs, cassettes and multiple chainrings. While the range of gears on hubs may be limited, they have the advantage of needing less maintenance, being simpler to use and have the ability to shift gears while coasting or waiting at a stoplight.

The bike may also have a front derailleur, which shifts the chain between chainrings attached to the cranks.

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The gears at the front effectively change the range of your gears, so that they are more suited to high speed, flat terrain or low-speed climbing. The cassette allows you to select your gear more precisely within that range as you increase or decrease your effort.

Front Derailleur

 

The gears are divided into two parts.

There are three chain rings in the front, which are controlled by the left hand gear shifter. That’s why there are 3 numbers to choose from on that gear shifter – to choose which of three front rings your chain will rest on. The “derailleur” attached to the gear shifter moves the chain from one ring to another.

 

 

 

When the chain is on the smallest of these three chain rings

1), pedaling will be very easy. This is called the granny gear. The second chain ring is for level, off road riding

2), and the third, or largest chain ring, is good for riding on good road surfaces..

 

So if you want to use just those three gears, you can certainly do so. But, using the right hand shifter, you can take advantage of the increments of gears available to you.

Rear Derailleur

Rear Derailleur Gears

 

The back chain ring is a cog set featuring seven, eight or nine cogs, depending on how many “speeds” you have (21, 24 or 27). Each cog is of a different size, and again, the smaller size cogs will enable you to pedal very, very easily – but not go very fast, while the larger size cogs will allow you to go further with each downward stroke of the pedal.

The best thing to do is to practice, practice, practice. Take your bike to a parking lot or somewhere where you don’t have to worry about people, and shift from one gear to another, getting used to each one and how easy or difficult it is to pedal while in that gear.

People new to biking might be rather wary of shifting gears. Shifting always was a bit problematic during the “old days” – when one only had a pair of center mounted levels to work with, but now gear shifters – the twist type – are so easy to use that there is no reason to be afraid of shifting. Again, as long as you’re pedaling while you shift, you won’t hurt the gears.

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Single speed/fixed bike

There is always have the option of just one gear,  that’s how bikes were originally designed.

Single speed bikes use a single cog that can freewheel and allows the rear wheel to rotate without the pedals moving.

Fixed bike or Fixies are even more rudimentary, with the rear cog ‘fixed’ in place, meaning if the bike is moving, the drivetrain moves, so you always have to pedal.