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What is A Bike Crankset — The Ultimate Guide To Heart of Drivetrain

The crankset is the heart of a bike’s drivetrain, and it majorly consists of chainring and crank arms.  

The crankset of a bike should be very strong, reliable, and lightweight for the rider to be able to pedal efficiently. 

My main goal with this guide is to enlighten you about what is a bike crankset, its types, components, purchasing factors, and more. 

By knowing all this information, you will be able to choose the crankset that’s right for your bike type and to ride efficiently. So, let’s talk about each concept related to the crankshaft one by one. 

What is a Bike Crankset

Bicycle Chainrings - Triple Crankset

The crankset is a part of your bicycle that is responsible for moving it. It consists of crank arms and chainrings. In modern bikes, axles and spindles are also attached.

There is a wide variety of gear available in modern bikes to suit different types of drives. This allows one to choose based on their riding needs.

The primary role of Bike Crankset

A bike crankset or groupset is a drivetrain component of a bike that converts the motion of the rider’s legs into rotational motion, which is then transferred to the bike’s rear wheel to propel the bike forward. The bicycle crank is usually connected to the bottom bracket axle, which is mounted in the bike’s frame.

The size and length of the bike crankshaft can affect the rider’s pedaling efficiency and comfort, as well as the bike’s overall gear ratios.

Types of Cranksets on a Bike

There are three main categories of cranksets for bikes:

1. Single Crankset

A single-ring crankset has only one chain ring. This technology has been widely adopted by the mountain biking industry. The single chain ring compensates for the loss of the smaller inner ring by using a cassette with a wider range.

This reduces the number of moving parts, which reduces the likelihood of the chain coming off and places for mud to collect when riding off-road.

2. Double Crankset

The double crankset provides a greater number of gears with small steps between them, allowing riders to maintain a consistent cadence (pedaling speed).

These are available in a variety of sizes based on the type of road riding and rider fitness.

3. Triple Crankset

An older design of chain set is usually seen on vintage, touring, or less expensive bikes. It provides a fairly wide range of gears but also adds weight because of the third chainring.

The “granny ring,” or the smallest ring, will provide additional support for beginners on difficult climbs.

Parts of the Bike Crankset

Typically, bike cranksets have two major components: crank arms and chainrings. Let’s take a closer look at each of them one by one:

Crank Arms

The term “cranks” refers to the pair of crank arms. Located at an angle of 180 degrees, the two crank arms are connected by an axle. The axle is located in the bottom bracket. Steel, aluminum, and carbon fiber are just a few of the materials that can be used to make crank arms. 

Steel cranks were common on earlier, simpler bikes. In contrast, most entry-level to midrange crankshafts today are made of aluminum. While carbon fiber cranks are typically used only in high-end cranksets for racing.

The Bike Crank Arms are often used as an accessory part to the Bike cranks. The main function is to connect one side of the bike crank arm to another side. It also helps to transfer weight from one side to another and strengthen the bike cranks.

Note: Mostly, all road and mountain bikes use aluminum cranks because they are strong, stiff, and light for the price. 

Chain Rings

A chain ring is a component of a bicycle’s drivetrain that is attached to the crankset and converts pedaling motion into rotational motion to drive the rear wheel. 

The chainring is connected to the pedals and is located on the right side of the crankshaft. It has teeth around the perimeter that engage with the chain and transfer power from the pedals to the rear wheel.

Road bikes typically have two or three chainrings, while mountain bikes typically have one or two. The number of chainrings and their size (measured in teeth) determine a bike’s gearing, which influences how easy or difficult it is to pedal the bike.

A larger chain ring provides a higher gear, making pedaling easier, whereas a smaller chain ring provides a lower gear, making pedaling more difficult. 

In a bike crankset, chainrings are the gears that drive the front wheel. There are several types of chainrings, including:

Single chain ring

As the name suggests, this type of chain ring has only one cog and is commonly found on single-speed or fixed-gear bikes.

Double chain ring

A bike crankset with two chainrings is commonly referred to as a “double.” This type of chain ring is usually found on the road and on touring bikes.

Compact chainring

A compact chain ring is a type of double chain ring that has a smaller size, typically 34 or 36 teeth, compared to traditional road chainrings, which usually have 39 or 53 teeth.

It’s important to select the appropriate chain ring for your riding style and the type of terrain you’ll be riding on. The number of chainrings, as well as their size, can have a significant impact on your bike’s performance and gear range. 

Triple chain ring

A crankset with three chainrings is referred to as a “triple.” This type of chain ring is typically found on mountain bikes and provides a wide range of gears for different terrain.

The Different Crankset Options for Different Types of Bikes

Each bicycle model has a specific crankshaft type that works to provide riders with the best possible performance. Here are the crankset types available for each bicycle build:

MTB Bikes

Mountain bicycles use a single crankset. The machine has fewer moving parts with the single-ring crankset. It allows for a lighter bicycle weight, which is beneficial for mountain bike riders climbing on specific terrain.

Furthermore, without the front derailleur and shifter, fewer adjustments are required, making the bike ride simple.

Road Bikes

Double crankset technology is commonly found on road bikes. Riders can maintain a consistent tempo thanks to the double crankset’s variety of gears, which have small increments between each pedaling speed.

Bikes for Vintage, Touring, and Low-Cost

Triple-ring crankset technology is commonly found in vintage, touring, and low-cost bikes. Most inexpensive mountain bikes use the 3x crankset option as an alternative, which is considered obsolete.

BMX bikes

Crank arms, crank spindles, any necessary bolts, and spacers comprise BMX cranksets. Like all BMX components, they must be durable and capable of withstanding hard impacts on the concrete rail.

Therefore, most BMX cranks are made out of steel, while higher-end cranks are made out of lighter materials like aluminum or even carbon fiber.

How do I know what Crankset I need?

When determining the best crank length for you, consider your height, cycling discipline, and personal preference. You will be able to determine the best crank to use for your bicycle by considering the following factors.

Chain line

The crankshaft must have the correct chain line for your bike, which is the distance between the center of the chain and the center of the bike frame.

Chainring Compatibility

Ensure that the bike crankset you have selected is compatible with the type of chain you have and the number of chainrings you want. A double crankset (two chainrings) is standard on most road bikes, while a triple crankset (three chainrings) is optional on some mountain bikes.

Swapping  chainring sizes 

When switching chainring sizes, compatibility becomes a big issue, which further impacts chain shifting smoothness. Chain rings that are mismatched will shift awkwardly from small to large rings, increasing the chances of the chain falling out completely.

Hence, you should consider the sizes of rings recommended by bicycle groupset brands if you want a smooth and efficient ride. 

Length

The crankset length should be equal to or greater than the length recommended for your leg length.

Drivetrain Compatibility

Ensure that the crankset is compatible with the rest of your bike’s drivetrain, including the derailleur, chain, and cassette.

If you have any questions about any of these points, consult your bike manual or contact the manufacturer. It’s also a good idea to have the crankset installed by a bike shop to ensure proper installation and compatibility. 

Factors to consider when choosing a Bike Crankset

There are many factors to consider when choosing the best crankset. For your convenience, some of the primary ones are listed below.

1. Compact vs. Standard Chainsets

Compact chain sets are cranksets that have smaller chainrings as well as a shorter crank arm length in comparison to standard chain sets. The smaller chainrings create a lower gear ratio, making it easier to turn the pedals, as well as making it more suitable for climbing hills and going up steep slopes. 

A standard chainset, on the other hand, is designed for flat and fast riding because it has a higher gear ratio that makes it easier to maintain speed. The choice between a compact and a standard chain set will be determined by the intended use of the bike as well as the rider’s personal preferences. 

A recreational rider, for example, may prefer a compact chainset for a more relaxed and comfortable ride. While a road racer may prefer a standard chainset for its performance benefits.

2. Crank Lengths

When selecting a bike crankset, the length of the crank arm is an important factor to consider because it affects pedaling efficiency, comfort, and power. A longer crank arm provides more leverage, making pedal turning easier.

As a result, it is ideal for riders with longer legs who want to generate more power with each pedal stroke.

A shorter crank arm, on the other hand, allows for a more compact pedal spindle, which is ideal for riders with shorter legs or who prefer a more comfortable and relaxed riding position.

It’s also worth noting that a shorter crank arm can lower the risk of knee pain by reducing stress on the knee joint. 

3. Bolt Circle Diameter

The BCD is the circumference of the circle formed by the chainring bolts. It is an important consideration when selecting a bike crankset because it must match the BCD of the bike frame.

A mismatched BCD can cause poor chain alignment, resulting in poor shifting performance and increased wear on the chain and chainrings.

BCD sizes for road bikes are 130mm and 110mm, while mountain bike BCD sizes are 104mm and 64mm. To determine the correct BCD for your bike frame, consult the specifications provided by your bike manufacturer.

4. Chainrings 

The number of chainrings on a bike crankset determines the rider’s available gear range. Most road bikes have a double chainset (two chainrings), but some high-end models have a triple chainset (three chainrings).

The gear ratio and overall performance of the bike crankset are also affected by the size of the chainrings. Smaller chainrings have a lower gear ratio, which makes pedaling easier, while larger chainrings have a higher gear ratio, which makes maintaining speed easier.

Understanding Bike Crankset Sizes and How They Impact Your Ride

The size of the cranks on a bike is determined by the bicycle frame construction. Various types of cranks come in three standard lengths:

There are, however, several bike component manufacturers that make road bike cranksets ranging in length from 165mm to 180mm per level of the group set. Numerous specialist brands also offer cranks with lengths as short as 115mm, which is a considerable reduction in size.

Note: You can improve your cycling efficiency by determining the proper crankset size.

A Comprehensive Overview of Chainset and Crankset Differences

The terms chainset and crankset are used interchangeably to refer to the same component in a bicycle. Basically, the chain set is the combination of chain rings, cranks, and the bottom bracket spindle that drives the chain to move the rear wheel of the bike.

In essence, there is no distinction between chainsets and cranksets. Both terms refer to the component of a bicycle that turns the chain to convert pedaling force into forward motion.

However, in the United States, the term “crankset” is more commonly used, whereas in Europe, the term “chainset” is more commonly used.

Regardless of what it’s called, the chainset/crankset is an important component in any bicycle, as it determines the gear ratios and overall performance.

More Efficient and Durable Alternatives to the Standard Crankset

A bike crankset, also known as a chain set, is a bicycle component that converts the rider’s pedal power into rotational energy that drives the chain. There are several alternatives to a standard crankset, including:

Single-speed cranksets

They have only one chainring and are intended for use on single-speed bicycles.

Compact crankset

A compact crankset has smaller chainrings than a standard crankset, resulting in a lower gear ratio for easier hill climbing.

A triple crankset

It has three chainrings and a wider range of gears, making it suitable for a wide range of riding conditions.

Octalink cranksets

It uses an eight-spline interface between the bottom bracket spindle and the cranks to provide a more secure and efficient connection.

A direct-mount crankset

Direct-mount cranksets are a type of crankset that attaches directly to the frame without the use of a bottom bracket. This results in a stiffer and lighter setup, making it ideal for high-performance road and mountain biking.

Direct-mount cranksets eliminate the need for a bottom bracket, reducing weight and increasing stiffness, resulting in improved power transfer and handling. Direct-mount cranksets are also easier to install because they do not require the installation of any additional components, such as a bottom bracket. 

Electric assist cranksets

They have a motor integrated into the bottom bracket that provides the rider with electrical assistance.

These are only a few alternatives to a standard crankset. The type of crankset you select will be determined by your riding style, bicycle type, and personal preferences. 

Factors that affect Crankset compatibility 

The compatibility of cranksets is determined by several factors, including:

Bottom bracket standard

The size and the type of bottom bracket that a crankset will fit into are referred to as bottom bracket standards. It is critical to select a crankset that is compatible with your bike frame’s bottom bracket standard because a mismatched bottom bracket can result in poor performance and increased wear on the crankset.

BSA (British Standard), BB30, PF30, BB86, and BB90 are all bottom bracket standards. Each of these specifications has its own dimensions, axle length, and spindle size, which determines the type of crankset that can be used with it.

To ensure a perfect fit, various bottom bracket standards might also require particular bottom bracket cups or adapters. You should consult your bike’s manufacturer’s specifications to make sure you select the right crankset and bottom bracket standard for your frame. 

Try selecting a bike crankset that offers the functionality, dependability, and compatibility required for your riding demands by taking the above-mentioned variables into account.

Chain line

The chain line is the line along which the chain runs. The bicycle groupset must be designed to work with the bike’s specific chain line.

Bike Chainring sizes

Cranksets are available in various chain ring sizes, such as 44/32/22 or 36/26. The chain ring size must match the rest of the drivetrain, including the rear cassette and derailleur.

Spindle diameter

The crankset’s spindle diameter must match the diameter of the bottom bracket spindle.

Mounting interface

Some cranksets use a proprietary mounting interface, limiting their compatibility with other brands or models. When replacing a crankset, make sure it is compatible with the rest of the bike’s components for optimal performance and reliability. If you are unsure about compatibility, consult a bike mechanic or the crankset and bike manufacturer. 

Buying new Crankset v/s Replace the old one

Whether to purchase a new crankshaft for a bike or simply replace parts is determined by a number of factors. If your crankset is worn or damaged, it is best to replace it entirely. This will ensure that all parts are compatible and perform optimally.

However, if only a single component of the bicycle groupset is damaged, such as a chain ring or a pedal, it may be more cost-effective to replace that component only. This is less expensive and allows you to keep using the rest of the crankset.

When thinking about replacing a bike crankset, consider the type of riding you do and the level of performance you require. If you are a serious cyclist or racer, it may be worthwhile to invest in a high-quality crankset to improve your performance.

Finally, whether you buy a new crankshaft for a bike or replacement parts will be determined by your specific needs and budget. You may want to seek advice and recommendations from a local bike shop based on your specific situation.

How much does the Bike Crankset cost?

The price of a bike crankset can vary greatly depending on several factors, including the material used, the brand, and the model.

The following are some general price ranges for various types of bike cranksets:

Budget/Entry-Level Cranksets

These are available for as little as $30 to $50. They are typically made of basic materials such as steel and are intended for light recreational riding.

Mid-Priced Cranksets

These can range from $50 to $200. They’re made of more advanced materials, such as aluminum or carbon fiber, and are intended for more difficult riding conditions.

High-End Cranksets

They can cost anywhere from $200 to $500. They are made of high-quality materials such as carbon fiber and are intended for professional and competitive riders who require the best performance and durability.

It’s important to remember that a crankset is only one component of a bicycle, and the total cost of a bike can vary significantly depending on the type, style, and components included.

To Wrap Up — Bicycle Groupset

I hope by now you know what is a bike crankset and why it is the most important part of your bicycle. In essence, it’s the heart that moves a bicycle.

We discussed various details about the bike crankset and answered some FAQs regarding the same. Hopefully, most of your questions are answered.

Still, if you have any suggestions or doubts or something that I have missed, feel free to drop a comment below. I will be more than happy to assist you with your query. Please follow our Facebook Page for more guides like this.

So, now choose the best crankshaft for a bike while ensuring to follow the basics as discussed in this article. Happy cycling!!

Bike Crankset — FAQs

What does the Crankset attach to?

A bike crankset, also known as a chainset, is a bicycle component that connects to the bottom bracket axle. The bottom bracket is the component that secures the crankset and allows it to rotate freely. 

When should the Crankset be replaced? 

When you notice signs of wear and tear on your bike crankset, it is time to replace it. Some indicators include knocking noises, a visible bend, or damage that may necessitate the purchase of a newer model. 

What materials are cranks made from?

Cranks being one of the most important parts of a bike are made up of various types of materials depending on the requirements. Most of the cranks are made up of steel. It is the most cost-effective solution out of all, which gives very high strength to the cranks. 

It has only one disadvantage, and that is its weight.  Hence to reduce weight, some manufacturers go for aluminum also. Aluminum is light in weight and has less strength than steel. It is also possible to find high-end bikes with carbon fiber cranks if cost is not a concern. These are very light and super strong. 

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Hey Folks! I’m Jacob. I am a passionate, adventurous cyclist and my biking philosophy is to have fun, I felt the need to share my knowledge and learn more about bikes. I always ensure I adhere to all road rules. I hope that you will give biking a try. It’s a great way to get fit and have fun.

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