Bike Cranksets Buyer Guide (BMX ,MTB, Road Bike)

The drivetrain is one of the most essential parts of your bike. It features numerous components and additions that work to ensure your bike can be propelled forward and give you control over almost everything happening to the bike. Without the drivetrain, you will probably be pedaling to no results and remain in the same position.

The crankset comes in a variety of different forms and with numerous different components that make it functional. Cranksets have developed significantly over recent years and you will need to have some basic understanding to ensure your bike is functional. A good crankset will enable you to move forward with your bike effectively.

If you are inexperienced when it comes to cranksets, the following article should be a good thing for you. We will dive into some of the components that make up the crankset. The main focal point of the article is to help you better understand the crankset and enable you to make sure that you can use the components to their full extent.

Bike Cranksets Buyer Guide

Understanding The Crankset

If you are new to the world of cycling, you should consider the crankset and look deeper into some of the components. Before we look at some of the differences related to the crankset, we should show you all the different components. Here are all the components to keep in mind when looking at the crankset of a bicycle:

Crankset main parts


The cranks are two of the most important parts of the bike and they enable all the components to be set in motion. Two cranks are mounted on either side of the unit at an angle of 180 degrees to one another. They are connected by an axle that connects to the bottom bracket and the pedals are commonly attached to the cranks.

Depending on the bike you choose, you will come across a variety of different cranks. Most modern cranks are made from aluminum, but you could find them made from steel or even carbon fiber. Unfortunately, carbon fiber is expensive. Due to the price, it is worth noting that cranks are made from aluminum to shed some weight.

For entry-level bikes, you might find the steel cranks working. However, they are heavy and they could add some additional weight to the unit. Road bikes and BMX bikes need weight to be as low as possible, which means that the crank material is often aluminum. The aluminum materials will work wonders to reduce the weight.

In terms of replacing the cranks, the length also needs to be one of your main considerations. Many people neglect to look at the weight and buy the standard cranks. However, 175mm might not be comfortable for all riders. If you have longer or shorter legs, you might want to look at the different sizes like the 165mm cranks or 180mm cranks.


The chainrings are another important component that connects to the crankset. It has the responsibility of propelling the bike in a forward motion and driving the rider as the pedals are moving. The number of chainrings will vary depending on the bike and other components like the size will also be impacted by the discipline.

When it comes to performing stunts like using BMX bikes, the single chainring will do the job of moving the bike forward and allowing the rider to comfortably pedal. However, more technical disciplines like road or mountain biking might be slightly more complicated. Riders might need different speeds to help them achieve performance.

Bottom Bracket

The bottom bracket is another one of the top components that you might need to look into. The bottom bracket is what many people consider the driving force behind the complete crankset. Bottom brackets have also evolved significantly, with some of the older types being locked in the frame as cartridge bottom brackets.

While these are easy to control and replace, they add additional weight. Modern bottom brackets have an external design and the bearings are located on the outside of the crankset. With the bearings on the outside of the frame, it is much easier to make adjustments. It also strips away some of the unnecessary materials that add additional weight.

You might find that the newer bottom bracket versions are more expensive. However, they are designed for performance and to ensure that you have plenty of comforts. If you plan to upgrade it to the modern version, you might want to have a professional assist you in making sure that every component is perfectly fitted.

Different Cranksets For Different Disciplines – Deep Dive

To fully understand how the cranksets operate, you need to break it down into different disciplines. We must look at all the different crankset options available to ensure that you know how these components work. The following section will look at each of the top bike disciplines to help you better understand the cranksets.

Mountain Bike Crankset

The mountain bike is probably the first bike for most people and these cranksets are some of the most common. A mountain bike crankset will vary depending on the bike and the specific discipline of cycling that you are targeting. 

MTB bike

Most of the older cranksets used to have numerous chainrings in the front and these would vary in size and teeth. However, modern mountain bikes are now fitted with the more advanced single chainring, but the rear of the drivetrain has more chainrings at different speeds. Not only does it reduce the overall maintenance of the bike, but it also reduces the weight significantly.

The mountain bike cranksets can be broken up into a couple of components and these components are where the main differences come into play:


The mountain bike will have a traditional crank that can be used for your comfort. The length of the crank is traditionally around 175mm. However, it can be elongated or even shortened depending on your height and the length of your legs. Cranks must be comfortable and allow you to propel the bike forward effectively.

Bottom Bracket

The bottom brackets are also standard and the cartridge bottom bracket is one of the most commonly traditionally used for the mountain bike. However, the external bottom bracket is also used to shed some weight on some of the more advanced mountain bikes and these have bearings on the outside.

It is recommended that those looking to replace the bottom bracket on their bike will take the right precautions and ensure that you look at the fitting and how the unit will mesh into one another to make it functional.


The most variable component of the mountain bike crankset is the chainrings. The chainrings can vary significantly depending on the bike and personal preference. As a mountain bike rider, you will need to determine how many chainrings you are going to need and how you will be using them. Here is a breakdown:

  • Single Ring: The single ring was never the most popular option, but nowadays, it has become one of the most popular options to consider. It features only a single chainring located at the front and numerous cassettes at the rear. However, the gear ratios have been significantly widened to ensure they are comfortable for those doing endure and cross country cycling.
  • Double Ring: The double ring is slowly starting to fade out and the introduction of the advanced single ring option by SRAM, means that the double ring does the same thing as the single ring, but adds more weight. However, you still have a variety of people choosing the double ring due to the design and functionality.
  • Triple Ring: You will rarely find the triple-ring cranksets. These cranksets are slowly being phased out by the introduction of the advanced single ring. The idea is that the larger cassettes enable you to significantly reduce the weight.

Mountain bikes are dependent on good components and cranksets and you will need to make sure that you find the one that is best suited for your bike. Compared to the road bikes, the MTB chainrings have fewer teeth and the gears are stronger. Fortunately, everything can be changed and modified to meet your specific needs.

Road Bike Crankset

Road Bike cranksets are worlds apart from the MTB cranksets and these are often harder to understand. However, the road bike crankset is made to emphasize speed and always keep you in a position to ensure that you have adequate speed and comfort. Here is our breakdown of the road bike crankset:

road bicycle

Chainsets Explained

The road bike chainset is one of the most versatile pieces of equipment and it can be categorized into two distinct categories. These categories include compact and traditional chainsets. However, you will need to understand how they work in practice.

  • Single Chainsets: Much like the single chainring on the mountain bike, the single chainset is similar to the road bike. Being pioneered by SRAM, these chainsets are functional and they provide a wider cassette. It enables them to add more different features and teeth to make it functional.
  • Traditional Chainsets: Due to the nature of cycling, traditional chainsets are still being used in the modern era. They consist of one large chainring that works best for harder cyclists and it works for climbing. Traditionally, the chainrings have 39- and 52-tooth chainrings. The smaller chainring is often used for things like making the pace and flat surfaces.
  • Compact Chainsets: While the above-mentioned options are functional for those that prefer a more traditional option, the compact chainring setup is becoming the go-to option. It spans the mid-point of the large and small chainring, which removes the need for the smaller one. They are more compact and typically feature a 34- and 50-tooth ring setup.


The crank on these road bikes is similar in length to most traditional bikes and they feature a standard length of 175mm. However, the length can be adjusted and changed depending on the need of the rider to make it more comfortable. Aluminum is often the material used the most for the crank, but high-performance and professional road bikes might opt for carbon fiber for even more reduced weight.

Bottom Bracket

The bottom bracket on the road bike is slightly more complicated and since this is one of the components that need to be the best, it is worth diving deeper into them. The bottom bracket on road bikes can be broken down into three separate sections. Here is the basic rundown of these three sections:

  • Cartridge: The cartridge bottom bracket is the more traditional of the bottom brackets and it features a small axle and internal bearings. All these components are contained on the inside of the small metal cartridge. They are slowly being phased out, but the technology can still be found in many budget road bikes.
  • External Bottom Bracket: Some the modern bikes have an external bottom bracket and these are designed to make life easier for those that want a hollow axle. Not only does the hollow axle reduce the weight, but it also increases the overall stiffness. With the design, the bearings are compressed into aluminum cups, which are threaded to the exterior of the bottom bracket shell.
  • Press-Fit: The press-fit option is also one of the main options you might find in many of the modern road bikes, especially the more expensive options. Generally, these bikes have bearing seats that are molded into the frame of the bike and the bearings are pressed directly into the shell of the bottom bracket. Replacing these can be done and the main purpose is to increase the stiffness of the frame and the pedaling.

Road bikes are slightly more complicated than some of the other bikes. However, the components are performance-driven and you will notice that these bikes will have exceptional performance when it comes to the road. The bearings are important, but the complete crankset is designed to increase stiffness, which also adds more pedaling power.

BMX Cranksets

The BMX crankset is one of the more basic cranksets and the cranks are often sold separately from the chainrings and the bottom bracket. When you think of the BMX drivetrain, it should come to mind that they are very basic. The main purpose of these components is to provide drive for the rider. However, durability is important due to the pressure and the stunts that come with riding a BMX.

BMX bike with rider

BMX cycling is one of the more intricate forms of cycling. When you think of the traditional BMX, you might be thinking of the X-Games. However, many people that use the BMX, often use it for competitive racing purposes. These are four different cranksets you need to consider when it comes to the BMX crankset:

  • One Piece: The one-piece option is one of the most basic options to consider. It is a single-piece crank with arms and a connection to the bike. These are often made from steel and they are found on entry-level bikes and bikes for kids.
  • Two-Piece: As the name would suggest, these cranksets are designed from two different components. They have the cranks on the one end and the axle that connects them. However, they are interchangeable with the three-piece as long as the axle is the same diameter.
  • Three-Piece: As you become more advanced, the three-piece crankset will be the better fit. These consist of three interchangeable pieces and they are found on some of the more advanced options.
  • Race Cranks: Race cranks should be functional when it comes to being competitive. However, they have some of the same fundamentals you would find in MTB cranks. With the Euro-style bottom brackets, you can find them in the two-piece and the three-piece designs.
Single BMX Cranksets

The BMX cranksets are not as complicated as some of the others. However, you will need to make sure that you have the right option to ensure you have some performance. It is important that you also look at the two intricate features of the BMX cranksets that make them functional and stand out from the others.

Crank Length

The crank length on the BMX is often shorter due to the nature of the bike. With a shorter crank, it can be much easier to ensure easier pedaling. They are often in the range of 170mm. However, you can find some of the smaller versions of up to 140mm, while also extending them to 190mm. It all depends on your skill level and performance.

Axle Diameter

The axle diameter is one of the things that people should consider when looking at the BMX crankset. If you are to change it, the BMX axle diameter is found in two sizes. The 19mm and the 22mm options are both functions. However, the spline is also important. You should choose between the 48-spline, 16-spline, and 8-spline. However, it is important to make sure that they are compatible with the bottom bracket.

Frequently Asked Questions

Now that you have some form of an understanding when it comes to bike cranksets, you also need to make sure you are ready to buy. We have found that some people might have a couple of lingering questions and these questions could influence their purchase. This section aims to help remove any doubt and answer as many questions as possible.

Does One Crankset Fit All Bikes?

Unfortunately, cranksets are not interchangeable on bikes and you will find that they are different. The design of the MTB crankset and the road bike crankset have different dimensions and they have a couple of different features as well.

Which Crankset Should I Buy?

While the guide we provided will give you some insight into the different cranksets, you also need to understand the brands. If you have a specific crankset for your bike, you should probably stay with that brand. However, having a professional assist you in the process of measurement and using the cranksets are also important.

Can I Replace A Crankset On A Bike?

You should be able to replace the crankset on your bike with relative ease. However, the right crankset needs to be found and this is one of the places where many people fall off the bus. You should consider working on the crankset or even having a professional assist you with the process.

Can You Change A Crankset At Home? 

If you are inexperienced with bikes, you might not have the tools or the skills to fix or replace the crankset at home. While it can be done in the comfort of your home, you could also mess up. If you don’t have the skills or the tools to do it correctly, you might want to consider hiring an expert.

Bike Cranksets Buyer Guide Summary

Buying a good bike crankset should not be that hard. However, you need to understand the buyer’s guide and know-how all of the smaller components work to ensure you find the right one. Keep in mind that bikes are malleable and changes can happen at any time to ensure that you have the right features and accessories. Let us know in the comment section if we have missed any important information or if you have any crankset-related questions.

About Martin

I am Martin, I am the author of this blog. My main interests include cycling. That's why this blog was created. I have always been interested in technology and how bicycles are made, so I built one myself.

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