A drill that keeps your bike rolling

This game is now over

Authors: Thomas McDaniel and Jack Luke

The often overlooked component of the bearing actually brings life to your bike. Without bearings, you will not be able to steer, roll, pedal or have a functioning powertrain.

Bearings can be found in your hubs, bottom brackets, earphones, suspension pivots, pedals, gear levers... the list goes on-basically, anything that moves on a bicycle will have some kind of bearing.

In this guide, we will introduce the different types of bearings commonly used on bicycles, how to measure the bearings on a bicycle, the reasons why one bearing is better than another, and how to maintain the bearing.

Loose balls, cage balls, bushes, needle rollers and sleeves are the main styles of bearings in bicycle frames and components. Here, we explain how each type of bearing is different from the other.

Bushings (also called bushings or sleeve bearings) are a type of sliding bearing used in shock mounts, cheaper pulleys, and shifters.

The bushing is the simplest type of bearing. It is just a sleeve located between two surfaces to reduce friction.

The loose ball bearing system includes:

The contact surface of the outer ring and the inner ring is processed into a smooth surface that matches the contour of the bearing, which is the basis of their operation.​​

Loose ball bearings are usually used anywhere in entry-level bicycles, including hubs, bottom brackets and earphones.

In the high-end market, most brands no longer use loose ball bearings. Although Shimano and Campagnolo are notable adherents, most of their hubs use very high-quality cup and tapered bearings. Shimano also uses loose bearings in its pedals.

Although they are the oldest, they can be better in many ways. They are angular contacts (more on that later), are relatively easy to maintain, and if adjusted properly, they can perform very well.

Loose ball bearings are sometimes held in cages, which are also called cages (hence the "cage bearing"). This is usually made of pressed steel and separates loose ball bearings from each other.

Although usually associated with low-end products, cage bearings are not universally bad-Campagnolo's CULT bearings are cage bearings and exhibit excellent performance characteristics. Cane Creek's Hellbender Neo bearing is another interesting concept.

Cassette bearings are the most common bearing type, except for the cheapest bicycles.

These are an integral unit and are usually pressed into the bearing bore.

A typical radial cassette bearing consists of the following parts:

These bearings cannot be adjusted or completely disassembled.

Cartridge systems require precision to function properly, but with the development of manufacturing technology, due to the increasing tolerances of hubs, frames, and component holes, they are used more and more.

Needle roller bearings, also called roller bearings, are relatively rare in the bicycle industry.

Pedals are an exception, which occasionally appear in headsets, but even so, they have lost a lot of advantages in the face of newer and cheaper technology.

In needle roller bearings, the bearing itself is cylindrical, not a ball bearing.

They can create incredibly smooth rolling and stable platforms, especially under high loads, but in the bicycle industry, people tend to avoid them due to the expense and complexity of creating a well-fitting surface.

If they mate improperly, they tend to fatigue quickly. Needle roller bearings are often replaced by multi-row cassette bearings to achieve the same effect.

The size of the loose ball bearing is determined by the diameter of the ball bearing itself. This is usually expressed as a fraction of inches: 3/16 inch (4.7625 mm).

The exact size of the required bearing varies from component to component.

It is usually also possible to replace the cone in a loose ball bearing arrangement, but the outer ring (especially in the hub) is not often replaced.

The size of a cassette bearing is determined by its inner diameter (ID), outer diameter (OD) and width.

The measurement takes the form of "15x24x5mm" or similar.

They usually have a corresponding universal identifier, for example, in the case of the above-mentioned bearing, it will be 6802.

Using a caliper, you can measure the ink cartridge so that you can easily find replacement parts.

Headphones have unique characteristics because they have a slanted race. Their size may be more like "46.9 x 7 x 45°" to identify the outer diameter, width and angle measurements of the bearing races respectively.

Regarding performance, in general, the larger the ball in the bearing, the better, because increasing the diameter has an exponential factor for increasing the contact. More contact means more uniform force distribution and leads to better rolling performance and durability.

In recent years, several major wheel manufacturers have been pushing for larger bearings, and wheel hub sizes have continued to increase.

Two types of cassette bearings are commonly used in bicycles: radial contact and angular contact.

Radial bearings are the most common because they are cheaper. They try to carry the load in a true radial direction, which is vertical in terms of the hub, crank, suspension pivot or derailleur pulley.

Subsequently, they sacrifice a small amount of performance because the forces in these moving parts usually have an associated non-radial vector. Therefore, they must compensate with reduced tolerances.

In short, the accuracy of the radial cartridge system is low. Therefore, they do not have any directional applications—no internal or external.

As a benefit, because they are slightly less dependent on tolerances, they can be used for less expensive applications.

In contrast, angular contact bearings require tight tolerances because they are oriented. There are internal and external components, and they can be compared with the old cup-cone system in terms of design.

They supplement the radial and lateral force loads imposed by the rotating parts of the bicycle, but require extremely high tolerances in the mating holes to achieve precise fit and rolling performance.

In most cases, angular contact is the most suitable application for wheels, cranks and suspensions. However, many wheels and frames do not have matching holes to supplement the accuracy of the corner box.

This precision is where brands such as Industry 9, Chris King, White Industries, Phil Wood, and Alchemy Wheel Works have gained reputation.

You will usually see bearings called "ABEC" followed by a number (for example, ABEC 1, 3, 5, 7, and 9).

In short, the higher the number, the higher the quality of the bearing. It is a rough "good, better, best" indicator, but Chuck Panaccione of Enduro Bearings said it lacks this standard.

The ABEC standard defines the hole diameter (acceptable change in the size of the inner hole of the bearing), parallelism (change in width) and radial raceway runout (change in the groove where the ball is located).

But Panaccione made it clear that the ABEC system gave up load handling, ball accuracy or Rockwell hardness (material hardness).

The employees of Enduro Bearings believe that for bicycles, materials are much more important than ABEC grades, and for most applications, ABEC 3 and 5 are suitable for all bicycles.

As for levels 7 and 9, this level of accuracy is suitable for equipment that rotates thousands or hundreds of thousands per minute-which is a bit overkill for bicycles.

Cartridge bearings are usually sealed with two rubber seals on either side of the bearing.

They may sound like a boring topic (pun), but they have a great impact on the overall performance of the bearing (eyyy).

There are three main considerations for seals-friction, protection, and suitability.

Friction is the main point of contention for cassette bearings. Although the smaller the better, a little friction may indicate protection.

The function of the seal is to prevent the entry of grease and prevent the entry of contaminants.

However, once contaminated, can you clean and repair the ink cartridges without damaging the seals?

For most high-quality bearings, including every bearing manufactured by Enduro Bearings, Panaccione guarantees that "the seal can be removed from the inner ring for repairs using a small blade and careful hands."

The bearings are made of a variety of materials. Some examples include chrome steel, 440C stainless steel, XD15 super nitrogen stainless steel, and silicon nitride (ceramic bearings).

Generally speaking, the harder the material, the better, but there is a point of diminishing returns.

Ultimately, too hard means the ball will become brittle, which is no better than too soft.

The application of balanced bearings (wheel hubs, cranks, suspension pivots, etc.), how much service you are willing to provide, and the selection budget are all factors that a brand must consider when choosing a bearing.

Like any moving parts on a bicycle, the bearings require repair. Higher quality bearings will have longer maintenance intervals, but no bearing is truly "install and forget".

Correct installation is also important for bearing life.

This may seem simple, but misalignment caused by improper installation is an important cause of premature wear.

In addition, if you use angular contact bearings, there is a reason why the seals are different in color-the black seal faces the centerline, while the red seal should face outward.

Proper bearing maintenance ends with proper lubrication, which can be anything from viscous, waterproof grease to thin, frictionless lubricating oil.

Depending on the application, the type of bearing system used, the frequency of maintenance, and the type of environmental exposure the system has experienced, the best lubricant will be determined.

For more information, check out our in-depth guide on how to repair bearings.

Jack Luke is the associate editor of BikeRadar and he has been studying bicycles all his life. Jack is always looking for the most fashionable new niche in cycling. He considers himself a gravel idiot, loves to make trouble, two preachers and hard climbing. Jack thinks riding a bicycle to sleep in the ditch after get off work, or accepting stupid challenges for the BikeRadar YouTube channel. He is also a regular contributor to the BikeRadar podcast. With almost encyclopedic knowledge of bicycle technology, from the most esoteric retro niche to the most cutting-edge modern equipment, Jack is proud to be able to find stories that would otherwise not be reported. He also particularly likes tan tires, generator lights, cup and cone bearings, and skis. Jack has been writing and testing bicycles for more than five years. Prior to that, he had worked in a bicycle shop for many years and was often spotted riding a variety of strange and wonderful machines. You can also often see Jack and his partner riding in their beloved tandem Cecil.

Subscribe to Cycling Plus magazine to enjoy a 30% discount on the store price and get an Altura Nevis Hi-Vis jacket! 

Sign up to receive our newsletter!

Thanks! You have subscribed to our newsletter.

Already have our account? Sign in to manage your newsletter preferences

By entering your details, you agree to BikeRadar terms and conditions and privacy policy. You can unsubscribe at any time.

Subscribe and choose your bonus reward!

Subscribe to Cycling Plus to enjoy 30% off RRP Altura Nevis jacket