Mountain bikes are powered by drivetrains that are responsible for the continuous movement of these two-wheeled vehicles. Without these, bikes won’t move and the pedaling motion that you do will be useless.
But how do these drivetrains work? First of all, it’s important to know that drivetrains have multiple parts, one of the most important ones being the gears.
There are different gear numbers depending on the kind of bike. But the most common one is the 7-speed variants.
This article aims to dive deep into 7-speed bike gears and discuss their importance, uses, and the other things related to knowing more about the engine of your bike, the drivetrain gears.
What is a 7-speed bike?
A 7-speed bike is a kind of bicycle that has a drivetrain with 7 gear speeds. Although this depends on the number of chainrings a bike has, a 7-speed bike usually means that there are 7 cogs found at its rear.
This serves as the speed option for the rider. The cogs also vary in size, ranging from the biggest to the smallest.
Shift to the biggest cog if you want to have more power when climbing uphills. On the other hand, you can shift to the smallest cog if you want to go as fast as possible when riding downhills or flat section trails and paved roads.
It’s all a matter of knowing your required speed so you can choose the right gear.
Important Terminologies to Know
The first term you should know is the chainring. The chainring is a ring that has multiple teeth on its sides. This can be found on the front section of your drivetrain. It is also attached directly to your right crank, just on the side of your right foot.
A cassette is a group of sprockets or cogs found at the back section of your drivetrain. This contains multiple cogs or gears ranging in different sizes. It usually has 7 cogs in it, which means that it is a 7-speed bike.
However, there are higher-end models that have more cogs. The top-of-the-line bikes have 12 gears in total.
Derailleurs are the technical component of a drivetrain that is responsible for shifting your gears. In simpler words, it moves your chain to another cog so you can gain the required speed and amount of effort needed to go past trails.
Most budget bikes have a front derailleur and rear derailleur. Meanwhile, premium bikes that have 1x drivetrains only have a rear-wheel derailleur.
A sprocket is also known as a cog, which is among the many cogs located in the cassette. Each sprocket has its own size, which is different from its other counterparts. Their number of teeth also varies from each other.
The ratio is the relationship between a chainring and a sprocket. An example of this is 11-28, which means that you are running on an 11-teeth chainring and a 28-teeth sprocket or cog.
Teeth are the small spikes that protrude on the sides of a chainring and cog. They are also referred to as the letter “t”.
The drivetrain is a collective term of all the components that make up your bike’s engine. This covers the shifters, front derailleur, rear gears derailleurs, cranks, chain, and cogs.
How Gears Works
Gears work by simply multiplying the number of sprockets found on your rear drivetrain and the number of chainrings you have beside your crank arms.
If you have a 2x drivetrain along with 8 cogs or sprockets, then you have a 16-speed bike. The most common ones you’ll find these days are 21-speed and 24-speed bikes as they can be used both on roads by road bikes and on trails even by hybrid style bikes.
Meanwhile, a 7-speed bike is usually used for dirt jumps or trials because you don’t need to change speeds when you’re in these mountain biking disciplines.
So, how many gears do downhill bikes have to shift gears efficiently?
Downhill bikes also have 7-speed drivetrain setups because of their convenience for high-speed descents and safety in avoiding loose chains. Having more gears just complicates the gear range and mechanism for shifting gears from the easiest gear.
Low Gears vs High Gears
Every mountain biker needs to know that there is a low gear and a high gear. Low gear is also called easy gear because you don’t need to exert a lot of effort to push the pedal with your foot and to move.
This is useful when it comes to climbing. Think about biking towards the top of a hill and exerting a lot of effort.
Chances are, is that you can climb it and you’ll just stall. That’s where low bicycle gears come in because they are built for low-speed scenarios such as climbing cross-country uphills.
A low gear setting means that your chain is on the small chainring and a large cog on the cassette. You then downshift if you move from high gear to low gear.
On the other hand, the high gear is the speed setup that you’ll use when you’re in high-speed situations. This is used mostly when you are descending downhills and sprinting on flat section trails or pavements.
Being on a high gear setting means that your chain is running on the largest chainring and the smallest cog on your cassette. This is where you need to exert a lot of effort to move your bike. Note that upshifting is the term used when you are moving from low gear to high gear.
In the case of 7-speed bikes, high gear is when your chain is on the smaller cogs, while a low gear is when it is on the larger cogs.
What about chainrings?
The chainring is the disc that is directly connected to your right crank arm. This determines the kind of drivetrain you have.
If you have just one chainring, then you have a 1x drivetrain. 7-speed bicycles are usually 1x in nature because they only have one chainring connected to 7 cogs at the back.
Meanwhile, 2x and 3x drivetrains have two and three chainrings, respectively. These are common among budget mountain bikes.
The trend these days moves towards 1x drivetrains because they are lighter and more efficient. There is also no need to be running on unnecessary and redundant gears.
Removing the need for multiple chainrings means that there is less room for mechanical failure. This led to the growing popularity of 7-speed bikes.
Many people are opting for mountain bikes with a 7-speed drivetrain gear because it is less prone to mechanical failure, is more efficient, and is capable of moderate uphills and aggressive descents.
This is the reason why most, if not all downhill bikes, have a 7-speed drivetrain. Although it’s not the best when it comes to full-on cross-country mode, it still works best if you’re in for reliability and pedaling efficiency.