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Chainrings are mounted to your cranks and are at the heart of your drivetrain setup. Despite being a relatively simple component, chainrings come in a variety of styles, configurations, and compatibilities. This guide will help you decipher all these aspects so you can choose the best chainring setup for your drivetrain gearing.
The first thing you will need to consider when purchasing chainrings is what type of gearing setup you are building. The 3 main types are single (aka 1x), double (2x), or triple (3x). These numbers refer to the number of chainrings connected to your crank. Let’s look at each of these.
1x setups are the most common setup for modern mountain bikes but can are becoming more popular in the cyclocross and gravel grinding worlds and are starting to sneak onto some road bikes. Single ring drivetrains bring many benefits including reduced complexity of shifting, easier setup, lighter weight, and less clutter from shifters and cables on your bar. They can be built in a variety of gear combinations like 1x10, 1x11, and, most recently, 1x12. In these setups, the range of gears is handled completely with the rear derailleur and a matching wide range cassette. For those who seek ultimate simplicity, single rings are perfect for a single speed setup, swapping out the cassette and rear derailleur for a single cog.
While the cassette provides the range of gears, riders can choose to mount rings with various tooth counts to customize the gear ratio of their preferred setup. The most common tooth counts range from 28t-34t. Lower tooth counts will provide lower/easier gears for better climbing while higher tooth counts will equate to higher/harder gearing for faster descents. For MTB, smaller chainrings do provide more rollover clearance, so we recommend getting the smallest ring that stills allows for your needed gear range with your cassette.
Since a 1x drivetrain setup does not rely on shifting gears on a set of chainrings, the tooth profile of a single ring does not need any shift points or shaping to help move the chain from ring to ring. Instead, the tooth profile is designed to completely engage with the chain’s links, keeping the chain from skipping of the ring and ensuring a smooth and quiet drivetrain. These tooth profiles can be found in alternating narrow and wide teeth, taller teeth, or a combination of both. Some manufacturers are even designing specific chains that improve this engagement even further.
Another factor to consider, when buying a single ring, is offset. Offset is how far the outer edge of the ring is dished either towards or away from your frame and is crucial in ensuring proper chain line and maintaining clearance with the frame. As bikes have evolved, rear hub spacing has grown and moved the chain line with it. It is important to match the offset of your chainring to your rear hub spacing. We’ve broken that down into a simple chart:
While single ring setups are all the rage, 2x drivetrains are still holding a strong spot in both MTB and road cycling. 3x setups are quite a bit rare but can still be found on bikes focused on bikepacking or bike camping. Both 2x and 3x drivetrains can potentially offer a wider range of gearing. This is beneficial when the terrain varies dramatically or if a rider is planning to carry a lot of gear.
The primary advantage of 2x drivetrains for road cyclists is the ability for riders to match a cassette with small gear jumps between cogs with their 2x chainrings. These small gear jumps help to keep a steady and efficient cadence across a wide range of terrain. Due to the rough surfaces and varying terrain encountered while mountain biking, larger gear jumps are not nearly as noticeable.
With the rise in popularity of 1x drivetrains, we have seen a big shift to direct mount chainrings. These chainrings interface directly around the crank spindle and arm on the drive side. In the past, cranks used to have 4-5 arms (aka the spider) radiating from the spindle that the rings bolted on to. This allowed for multiple chainrings to be mounted. Early 1x setups removed the extra rings and mounted 4-bolt chainrings to the middle ring position of a 3x crank. It is possible to make a 2x crank into a 1x setup but requires additional spacers to get proper chain line. 1x dedicated drivetrains made the extra work and weight of these types of systems unnecessary.
There are many benefits to direct mount rings including overall reduced weight, decreased complexity or possible points of failure, and a more robust and stiffer ring for better power transfer. One downside is that it is a bit more work to swap rings because you need to remove your crank arm. For most people this isn’t a big deal since they rarely swap rings unless it is worn out. However, some brands have created an option for those who frequently change rings that mixes a direct mount spider with 4-bolt chainrings (link to Wolf tooth Camo and OneUp). This allows the rider to quickly modify their ring selection to match the terrain they are riding that day.
Many crank manufacturers will have their own proprietary direct mount profile. Whether you choose to go with a direct mount chainring or spider, you will need to ensure that you choose the correct DM interface to match your crank. Luckily, most aftermarket chainring manufacturers offer their rings for the range of interface options. We’ve added filters to our site in order to help you easily navigate the DM configuration, tooth count, ring shape, and offset.
Most chainrings come in a standard round shape but we’ve been seeing a growing trend of oval shaped rings. These rings have an elongated portion that is “clocked,” or set as a specific position on the ring, to deliver a more efficient pedal stroke and transfer of power. Some riders love oval rings while others don’t seem to notice the benefits or prefer round rings. Riders with knee pain often claim that the oval rings allow them to ride more powerfully without aggravating their knees. Ultimately, this is a personal preference, but both options should perform equally well.
For 2x or 3x drivetrains that use bolts to hold the chainrings in place, if you are replacing chainrings on your current crankset, you will need to determine the Bolt Circle Diameter (BCD). Often this number is printed on your existing chainrings, but if not, you will need to measure it. With 4-bolt cranks, measuring the BCD is quite easy. Simply measure the distance from the middle of one chain ring bolt directly across to the middle of the opposing bolt. For a 5-bolt setup, this is a bit more complex, so we’ve included a simple table that should help you. Measure the distance center-to-center of any 2 adjacent bolts, then use the table to find the correlating BCD.
There are always exceptions to rules. Some cranks have asymmetric bolt patterns that aren’t as easy to calculate. These almost always have the BCD printed on the rings but, if not, you will need to refer to the manufacturer’s website for accurate information.
When it comes to choosing the correct gearing for your 2x or 3x drivetrain there are several factors to consider; personal fitness, terrain, and current drivetrain setup all affect this choice. However, there are a few guidelines to get you started. Historically, 7, 8, and 9-speed cassettes had had narrow range, so to maintain decent gear steps and a useable range generally they were paired with wider ranged chainring combinations. Things are changing as wider range cassettes and 11 or 12 speed drivetrains are becoming more popular. Let’s look at these by discipline.
The most common tooth counts on a mountain bike triple crankset is 42-32-22, while the double cranks usually have 34/24 or 36/26 combos. There are variations to all these combinations that prioritize climbing (less teeth) or descending gearing (more teeth) and you can choose various tooth count chainrings if the BCD matches. Pairing 2x/3x crank with a wide range cassette can get you a broad spectrum of gears while keeping the steps between gears comfortably close, so your legs don’t get “shocked” by gear shifts.
Gearing remained consistent in the road world for a while and the “standard gearing” was established as 53/39 on most road doubles and 50/39/30 on a triple (much less common) matched to an 11-23t cassette. This gearing tended to be a bit “big” for a lot of recreational riders and the compact crank was born as 50/34 combo. This helped improve pedaling cadence and climbing ability but sacrificed top-end speed. As mid and long cage derailleurs and wide range cassettes become more common with the advent of 11sp and 12sp drivetrains, a new mid-compact crank was introduced that took advantage of the cassette’s gear wide range (11-28 or 11-32) to give improved cadence while still having good gearing for descending or climbing.
One thing to note, is that many 2x/3x road cranks cannot be converted to different ring size combinations. There are some newer models that are changing this trend by using direct mount spiders and rings, but it is not quite ubiquitous yet. Further, 1x drivetrains are becoming more popular in the road segment, especially on gravel, cyclocross and commuter bikes where cadence and small gear steps are less crucial, and simplicity of function is prioritized.
There are 2 major materials that most chainrings are machined from; steel and aluminum. Steel rings tend to be stronger, have a longer wear life, and cost less, but tend to be a fair bit heavier. Aluminum rings are plenty strong with a good wear life while being lighter, but they do cost more and wear out a bit quicker. Most riders choose to run aluminum rings, but if cost and durability are most important to you, the steel rings are a great choice.
There are several products that are designed to further protect your chainrings or to ensure that your chain doesn’t fall off. These chain guides and bash guards have several different styles, mounts, and functions to consider. We will take a deeper look into these in another guide.
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