Chainrings, also known as chain wheels, are the large, round gears attached to the crankset of a bicycle. They are equipped with teeth that engage with the chain. Chainring meaning refers to their role as a crucial part of the bike’s drivetrain—they help us transfer our pedaling power to the chain. When you pedal, the crank arms turn the chainring, which in turn moves the chain. The moving chain drives the rear wheel, making the bike move forward.
Cranksets usually have one, two, or three chainrings, depending on the bike's design and purpose. The number of the crankset's chainrings will decide your bike's gearing. Conventionally, most road bikes use two chainrings. As for newer mountain bikes, they use only one chainring. The reason is that they're simple, reliable, and offer all the gears most riders need. As a result, gravel bikes and even some road bikes all switch to using only one chainring.
Sizes of Chainring
The size of your chainring will determine how hard you pedal. Chainring size is usually measured by the number of teeth it has. For example, a "32t" chainring has 32 teeth. With more chainring teeth, it means a bigger chainring. Bigger chainrings offer you harder gears, which are better for speed.
As for smaller chainrings, they will make your pedaling easier. As a result, they are great for climbing or rough terrain. When choosing the chainring size, consider the following factors: Your fitness, where you ride, and your bike’s drivetrain setup. This also ties into your overall chainring ratio, which influences how efficiently you convert pedaling effort into speed or torque.
These are the common chainring sizes you will see on the market:
Road Bikes (Double Chainrings)
Standard: 53/39T
Semi-Compact: 52/36T
Compact chainring: 50/34T
Mountain Bikes (1x setups)
Common size: 32T
Easier gearing: 28T or 30T
Harder gearing: 34T
Gravel Bikes (1x setups)
Standard size: 42t
Types of Chainrings: Bolt-on and direct-mount
Chainring types are generally categorized based on how they are attached to the crankset.
Bolt-on Bolt-on chainrings use bolts to connect to the crankset’s spider. The spider is the extension coming out of the right crank arm that connects the chainring. Bolt-on chainrings are suitable for users who like to change gear setups because they are easy to swap out.
Direct-mount
As for Direct-mount chainrings, they are directly connected to the crank arm using a splined interface. This design is stiff and more secure. What's more, they are lighter than Bolt-on setups. They are commonly used in 1x drivetrains.
There are also some special chainring types. Narrow-wide chainrings have teeth that alternate in width to match your chain better, which helps prevent the chain from falling off. Especially great for mountain or gravel riders. Oval chainrings are shaped a bit differently from standard round ones. They maximize the pedal power and minimize the resistance. Therefore, they can help you pedal more smoothly for better efficiency. A great choice for long-distance riders.
Chainrings play a big role in your riding style. Road bikes require smooth shifting performance. They often have two chainrings up front and a lightweight design. On the other hand, mountain and gravel bikes mostly use just one chainring. Keeping the chain in place is more important than fast shifting in terms of mountain and gravel bikes. That’s why their chainrings are built to hold onto the chain tightly.
Things You Need to Know About Chainrings
Bolt Circle Diameter
The Bolt Circle Diameter (BCD) is the measurement of the circle that runs through the center of all the bolts on your chainring. You’ll need to know chainring BCD if you’re replacing a bolt-on chainring. BCD determines chainring compatibility.
In order to fit more properly, the new chainring needs to match the crankset’s BCD and bolt pattern. With smaller BCDs, we use smaller chainrings. For example, a 130mm BCD fits a minimum 38t ring, while a 110mm BCD can go down to 33t. Direct-mount chainrings don’t have a BCD because they are mounted to a splined interface on the back of the crank.
Materials of Chainrings
Chainrings are typically made from aluminum, steel, or carbon fiber. With different materials, the weight, durability, and performance will make a huge difference.
Steel chainrings are durable and affordable, but heavy. They are commonly used on entry-level bikes.
Aluminum chainrings are lightweight and rust-resistant. They are ideal for most performance bikes. As for Carbon Fiber chainrings, they are extremely lightweight and stiff but expensive. They are often used in high-end bikes.
Conclusion
In conclusion, chainrings are a key part of your bike’s drivetrain. They are responsible for converting your pedaling power into forward motion. The chainring size, chainring type, and material all affect how your bike performs. As a result, knowing and understanding your riding style is very crucial when choosing the right chainring.
The following factors are typically important when deciding on your chainring, chainring ratio, efficiency, and chain security. Whether you're riding on the road, tackling tough mountain trails, or cruising on gravel paths, chainrings definitely play a huge part in your riding performance.
