Bearings Buying Guide - SkatePro

Jul. 07, 2025

Bearings Buying Guide - SkatePro

Are you unsure which bearings you should get? In this guide, we'll explain the most important terms and facts about bearings. We'll also explain which bearings are best for exactly your way of riding or skating.

You can find more information on our web, so please take a look.

1. Bearings in general

A wheel needs 2 bearings to rotate on the axle. A bearing can have a big influence on the speed and feel of your riding/skating.
Regardless of the type of bearing you have, you should avoid sand, water and humid conditions at any time, as this will shorten the lifespan of your bearings considerably. Regular cleaning and lubrication of bearings can help to increase their durability and speed. See how to clean your bearings here.

Also, a spacer to fill out the space between the bearings is required, as to avoid destroying the bearings and to create clean rotation when the axles are tightened. The size of the spacer depends on the size of the axle used.

8 mm spacer

6 mm spacer

The quality of bearings depends on a range of factors, such as:

Material
Precision (ABEC)
Lubrication
Sealed or open (Removable Shield)

Which type of bearing is best for you:

Are you mainly riding/skating outside, we recommend sealed bearings lubricated with grease,
as these are most resistant to dirt & dust and require low or no maintenance.
Are you mainly riding/skating inside, you can use open bearings that spin fast and are easy to clean.
Are you interested in speed and long distance runs, you can use high precision bearings lubricated with oil. They spin extremely fast and are easy to clean, but dirt can damage them quickly.

2. Mounting

A bearing can usually be pressed in with your thumbs. When the bearing is mounted correctly, it is in line with the wheel core/hub. If it points out in one corner, it's not mounted correctly and will be destroyed upon skating it. If you have a metal core wheel it can be hard to mount the bearing, in this case, use a rubber hammer or a square piece of wood to knock it in.
Never use a metal hammer as it will destroy the bearing and your warranty.
Alternatively, you can use some lubrication to get a bearing in place, if you do then remember all excess lubrication has to be removed afterwards.

3. Bearings in detail

Material

The material of bearings is one of the most important factors for their quality and durability. Most bearings are made of steel. Cheap bearings are usually made of pressed sheet metal or hardened carbon steel, both types are not recommendable for a long lifespan.
Better bearings are made of real bearing-steel, such as chrome, titanium or Swiss steel.
In ceramic bearings (usually used for speed skating) the balls are made of industrial ceramic (Silicon Nitride). Ceramic balls seldom rust and are more durable than steel.

Price and quality are very closely related when it comes to bearings, and you can usually trust the known brands to produce good and durable bearings.

Precision/ABEC

Bearings are categorized according to the industry accepted ABEC-specification. ABEC describes how good bearings are at translating the force applied on them. The higher ABEC classes provide better precision, efficiency, and greater speed capabilities, but do NOT necessarily make the components spin faster. The ABEC rating does not relate to other critical factors, such as the precision of spacers and wheels or the material. All bearings do lose their precision level after some wear.

Please note, that not all brands make use of the ABEC scale (e.g. Bones) and that other scales for bearings exist.
ABEC stands for Annular Bearing Engineering Committee.

Lubrication

Bearings can either use oil or grease as lubrication. A bearing must never run "out" of lubrication, if it does it will melt and lose speed or block completely.

Oil: Results in high speed because of less resistance in the lubrication material. A thin oil gives higher speed, but also requires more frequent maintenance.
Grease: It resists water and dirt more than regular oil. Requires almost no maintenance, but creates higher resistance, also means less speed.

Notice: Water can remove all lubrication! If this happens and the water dries, your bearings will get very hot and possibly melt and make sounds, the next time you use them. This means you need to replace the bearings. In some cases, if you have not rolled on them in between, it can be saved if cleaned and oiled properly before the next use.

Shields/Seal

In order to prevent dirt, sand and water to enter the bearings, a shield or seal is often placed on each or one side of the bearing.

A Shield is usually a metal shield mounted to the outer ring and has a little space to the inner ring (also called a dustproof bearing). Bearings with shields have little friction and therefore rotate more easily, giving you more speed. On the other side is the bearing not perfectly protected against water and dirt.
A Seal (pictured below) is made of steel-enforced rubber, which is mounted to the outer ring, and slightly touches the inner ring. It gives better protection and almost no maintenance, but also higher friction and slightly lower speed.

4. The standards and bearing precision explained

There are a number of factors covered by the ABEC grades. One is the eccentricity (roundness) of the track in the inner ring. The table below is the maximum eccentricity allowed.

Type mm Inches ABEC 1 0. mm (0.") ABEC 3 0. mm (0.") ABEC 5 0. mm (0.") ABEC 7 0. mm (0.") ABEC 9 0. mm (0.")

This means, that the higher the ABEC classification, the smaller the deviation in the parts of the bearing = more power is transferred to the wheel.

ABEC and ILQ cannot be directly compared since ILQ is a brand name and ABEC is a standard.

ABEC bearings are measured on the accuracy in production and not the durability or function under a load. Twincam, the manufacturer of ILQ rates the quality of their bearings on a scale similar to the ABEC scale. But despite that, ILQ bearings has 6 balls, where ABEC bearings have 7.

To clarify the difference, ILQ is not a standard, such as ABEC bearings. ILQ should, therefore, be seen as an unrated bearing from a professional inline bearing manufacturer and is not optimal for industrial machinery.

Bones bearings are made purely for skating - and cannot be compared with ABEC specifications.

The vocabulary for bearings and their shields is listed below (the type of the bearing is usually printed on the bearing together with the size, e.g.: 608ZZ).

608

Standard bearing
22 mm outer diameter
7 mm width
8 mm inside diameter

688

Mini/Micro bearing
16 mm outer diameter
5 mm width
8 mm inside diameter

Shield, 1 metal shield
Open in the other end for easy maintenance (always turn the open side to the inside of the wheel when mounting)

Shield, 2 metal shields
The shields are mounted with a small C-ring, which must be removed in order to remove the shield for maintenance.

2RS/RS/RZ

Seal, 2 steel armed rubber seals
Seals mounted without C-rings. It is possible to remove the seals carefully with a needle for maintenance.

BRS

Types of Bearings – A Thomas Buying Guide - Thomasnet

What are Bearings?

Bearings are mechanical assemblies designed to facilitate motion by reducing friction between moving parts. They consist of rolling elements—such as balls or rollers—enclosed between inner and outer races, making them suitable for rotating or linear shaft applications. Various bearing types are available, each tailored to specific load capacities and motion requirements, including ball bearings, roller bearings, linear bearings, and mounted bearings. Specialized options, such as slide bearings, jewel bearings, and frictionless bearings, address unique performance demands through distinct construction features.

Additionally, sleeve bearings, journal bearings, and fluid-film bearings are categorized as bushings. These types operate with a thin lubricant film, enabling smooth motion and differentiating them from rolling-element bearings, which rely on direct contact between rolling components. In this article, we will explore the types of bearings, their applications, and essential considerations for selecting the right bearing for specific requirements.

Types of Bearings and Their Uses

Ball Bearings

Ball bearings are mechanical assemblies that incorporate spherical rolling elements positioned between circular inner and outer races. They support rotating shafts while minimizing friction between them and stationary machine components, providing a low-friction solution for rotational movement. Ball bearings are widely used in machinery with rotating shafts that require consistent, low-resistance support.

Key configurations of ball bearings include shielded and sealed types, each offering specific benefits for protecting against contaminants or retaining lubrication. Ball bearings are also standardized to enable interchangeability across different applications and industries, facilitating their integration in diverse machinery setups. Due to their design, ball bearings are commonly called rolling element bearings or anti-friction bearings.

Key considerations for ball bearings include:

High-speed or high-precision applications: Ball bearings are often the preferred choice in applications that demand high rotational speeds or precise movement.
A broad range of standardized options: A wide selection of standardized ball bearing types is available, ensuring suitability for various applications.
Versatile Load Handling: Ball bearings can accommodate radial loads (perpendicular to the shaft) and axial loads (along the shaft) in unique configurations, making them adaptable to different load requirements.

View over 900 Ball Bearings Suppliers on the Thomasnet Discovery Platform for your needs.

Roller Bearings

Roller bearings are mechanical assemblies featuring cylindrical or tapered rolling elements positioned between inner and outer races. These bearings support rotating shafts and minimize friction between moving shafts and stationary machine parts, particularly in applications requiring heavier load support. Roller bearings are designed to handle larger loads than ball bearings due to the greater contact area provided by their rolling elements.

Tapered roller bearings are a specific type that can accommodate both high radial and axial (thrust) loads, making them suitable for applications requiring robust, multidirectional load support. Roller bearings come in various forms, including cylindrical and spherical rollers, each tailored for different performance needs. Although roller bearings are standardized, they may have slightly less interchangeability than ball bearings.

Key considerations for roller bearings include:

Higher Load Capacities: Roller bearings offer greater load-carrying capabilities than ball bearings, making them ideal for heavy-duty applications.
Ability to Withstand High Axial Loads: Certain types, such as tapered roller bearings, are specifically engineered to support high axial and radial loads.

View over 600 Roller Bearings Suppliers on the Thomasnet Discovery Platform for your needs.

Mounted Bearings

Mounted bearings are mechanical assemblies featuring bearings encased within bolt-on or threaded mounting housings, such as pillow blocks and flanged units. These assemblies support rotating shafts and reduce friction between them and stationary machine components, especially in machinery with exposed shafting. Mounted bearings are commonly employed as take-up devices at conveyor ends and as flanged units at intermediate points along the conveyor. They are available in rolling element and journal bearing configurations, allowing versatility based on load and speed requirements.

Designed for straightforward bolt-on mounting, mounted bearings are optimized for easy installation and replacement, with some varieties—such as cartridge designs—further simplifying the replacement process. Additionally, rod end bearings and cam followers are other types of mounted bearings used for specific applications requiring precise alignment or tracking along a surface.

Link to Shangyou

Key considerations for roller bearings include:

Housed Units for Enhanced Protection: The housings protect the bearings and simplify mounting.
Easy Replacement with Cartridge Designs: These designs allow faster bearing replacements, reducing downtime.
Set Screws for Shaft Positioning: Set screws are commonly used to position the shaft within the bearing housing securely.
Adjustable Support for Components: Mounted bearings often allow for adjustments, enabling alignment and tension control in supported components.
Suited for Low to Medium-Speed Applications: While versatile, mounted bearings are primarily intended for applications with low to moderate speeds.

View over 150 Mounted Bearings Suppliers on the Thomasnet Discovery Platform for your needs.

Linear Bearings

Linear Bearings are mechanical assemblies that incorporate ball or roller elements within housings, enabling smooth linear movement along shafts. They are essential in machinery requiring precise linear motion and positioning, commonly found in automation equipment, robotics, and CNC machinery. In addition to supporting linear movement, some linear bearings, depending on the configuration, may also allow limited rotation movement along the shaft.

Key considerations for roller bearings include:

Lower Friction and Higher Accuracy: Compared to bushings, linear bearings offer reduced friction and enhanced accuracy, making them suitable for applications where precision and smooth motion are critical.
Higher Cost and Complexity: Due to their intricate design and high-performance materials, linear bearings are generally more expensive and complex than bushings.

View over 300 Linear Bearings Suppliers on the Thomasnet Discovery Platform for your needs.

Slide Bearings

Slide bearings are mechanical assemblies engineered to enable unrestricted motion in a single direction between structural elements. They are primarily used in structural supports for bridges, commercial buildings, and industrial facilities, where they accommodate thermal expansion, permit end-beam rotation, and help isolate structural components from vibration, noise, and shock. These characteristics make slide bearings essential for ensuring stability and durability in structures subject to dynamic loads or temperature changes.

In addition to their use in large structural applications, slide bearings are also applied in specialized equipment, including truss base plates, heat exchangers, and process equipment where controlled linear movement and load accommodation are required.

Key considerations for slide bearings include:

Thermal Movement Accommodation: Allows for expansion and contraction due to temperature variations.
End-Beam Rotation: Permits rotation at beam ends, essential for maintaining structural integrity.
Vibration and Shock Isolation: Helps dampen vibrations and minimize noise transmission, protecting the structure and its components.

View over 100 Slide Bearings Suppliers on the Thomasnet Discovery Platform for your needs.

Jewel Bearings

Jewel bearings are mechanical devices designed for light rotating applications with minimal loads, and the supported shafts are very small. They are commonly used in watches, meter movements, gyroscopes, and other precision instruments. Jewel bearings are typically constructed from synthetic materials, with ruby and sapphire being the most commonly used due to their hardness, wear resistance, and low friction properties. These bearings provide highly reliable and smooth operation for delicate, low-load mechanisms, making them ideal for applications that require exceptional precision and durability in small-scale moving parts.

Key considerations for jewel bearings include:

Load and Size Requirements: Jewel bearings are suitable only for applications with very small loads and minimal shaft sizes.
Precision Needs: Ideal for high accuracy and low friction applications like timekeeping and measurement devices.
Durability and Low Maintenance: Jewel materials like ruby and sapphire are wear-resistant, offering a long life with minimal maintenance.

View over 30 Jewel Bearings Suppliers on the Thomasnet Discovery Platform for your needs.

Frictionless Bearings

Frictionless bearings use air or magnetic fields to provide shaft support without physical contact, making them essential for high-precision applications that require ultra-low friction. These bearings are employed in advanced applications, including medical devices, aerospace systems, and precision manufacturing, where even slight friction can impact performance.

Key considerations include:

Friction Reduction Needs: Frictionless bearings are best suited for applications that demand extremely low or zero friction to prevent wear.
Operational Environment: Consider the application environment, as magnetic or air-based frictionless bearings may be sensitive to external magnetic fields or require clean, dust-free conditions for optimal performance.

View over 30 Frictionless Bearing Suppliers on the Thomasnet Discovery Platform for your needs.

Applications and Industries

Bearings play a crucial role across nearly every industry involving moving components or equipment. The variety of bearing types available allows them to meet the unique requirements of diverse applications:

Ball and Roller Bearings: Known for their versatility, ball and roller bearings are used in an array of machinery, from boiler feed pumps to automotive transmissions. They provide robust support for rotating shafts under various load conditions. Ball bearings handle radial and light axial loads, while roller bearings support heavier radial loads due to their larger contact area.

Mounted Bearings: These are common in conveyor systems, shaft linkages, and setups requiring extended shaft support. Housed in flanges, pillow blocks, or take-up units, mounted bearings offer stability in applications lacking enclosed housing (such as standalone shafts) and are often equipped with seals or shields for environmental protection.

Linear Bearings: Exclusively used in linear motion applications, linear bearings are ideal for setups like slide tables that require smooth, guided motion along a single axis. Selection factors include travel distance, load capacity, and precision, and they are often paired with ground shafts for dimensional accuracy and low-friction sliding.

Slide Bearings: Primarily utilized in large civil engineering projects, such as bridges, slide bearings support structural loads while allowing limited movement for expansion and contraction. Unlike other types that facilitate continuous motion, slide bearings focus on withstanding heavy, static loads while permitting slight positional shifts. They are often made with Teflon or stainless steel surfaces to minimize friction.

Jewel Bearings: Designed for light-load applications, jewel bearings are commonly used in precision instruments like watches and meters. Due to their hard surfaces and lack of rolling elements, jewel bearings are suited for small devices with intermittent motion requirements.

Frictionless Bearings: These include specialized types like air and magnetic bearings, used in applications that demand virtually zero friction and extreme precision, such as aerospace and high-tech manufacturing. Frictionless bearings operate without physical contact, eliminating wear from shaft contact and offering unparalleled smoothness.

Radial Ball Bearings: Used primarily for shafts under radial and light axial loads, radial ball bearings are the most common bearing type and are available in sealed or shielded configurations to retain lubricants and protect against contaminants. Angular contact ball bearings can handle higher axial loads in one direction, while ball thrust bearings are designed only for axial loads.

Roller Bearings: Available in shapes such as cylindrical, needle, tapered, and spherical rollers, these bearings have a larger contact area, enabling them to carry higher radial loads than ball bearings. Some roller bearings, like tapered roller bearings, are also suitable for high axial loads.

While bearings find uses across countless industries, certain sectors rely particularly heavily on them due to specific demands for durability, precision, cleanliness, or temperature stability. Key industries include:

Aerospace
Agricultural
Automotive
Machine Tools
Medical
Mining

Key Considerations for Bearing Selection

Proper bearing selection ensures optimal performance, efficiency, and durability. Several factors must be considered to match the bearing to its intended application, including friction, temperature, lubrication, load, speed, and environmental conditions. These considerations significantly influence the bearing’s reliability and lifespan.

Load and direction are essential, as bearings must support radial forces that act perpendicular to the shaft and axial forces that act along it. Roller bearings are better for heavy radial loads, while tapered or angular contact bearings handle significant axial forces or a combination of both.

Speed and precision are equally important. Ball bearings perform well in high-speed applications requiring accuracy, such as machine tools, while roller bearings are better suited for slower, heavy-duty operations. Bearings designed for high-speed use often include materials and features that reduce friction and manage heat effectively.

Another crucial consideration is misalignment tolerance. Bearings must compensate for shaft deviations without loss of performance. Ball bearings are suitable for minor misalignments, while spherical roller bearings are designed to accommodate larger ones.

Static and dynamic load ratings help ensure the bearing can withstand operational demands. Static loads are applied when the bearing is stationary and can cause permanent indentations or brinelling if they exceed capacity. Dynamic loads encountered during rotation distribute stress across the bearing’s surfaces, improving durability. Bearings are classified by load capacity levels, such as extra-light or medium-duty, to match specific requirements.

Environmental and operational conditions must also be considered. Bearings exposed to contaminants like dirt, dust, or moisture often require seals or shields. Shields provide light protection with minimal friction, while seals offer more robust protection but increase friction. Temperature tolerance is critical, as extreme temperatures affect lubrication and material properties. Lubrication requirements, whether grease or oil, must align with the application to ensure consistent performance and reduce maintenance.

Friction, temperature, and lubrication are interconnected factors influencing bearing efficiency. Bearings designed to minimize friction are essential for applications requiring precision and speed. Proper lubrication ensures smooth operation and longevity, while the choice of materials and design must accommodate temperature variations.

Thoughtful selection reduces downtime, enhances machine performance, and ensures long-term operational success. Table 1 below compares different types of bearings based on their load capacity, speed capabilities, and typical applications.

ABMA

The ABMA (American Bearings Manufacturers Association) establishes standards for various types of bearings to ensure quality, consistency, and interoperability across the industry. These standards cover critical aspects such as bearing dimensions, performance characteristics, and testing methods. The ABMA is closely affiliated with the ABEC (Annular Bearing Engineering Committee) system, which provides a widely recognized scale for rating the precision and tolerance of ball bearings. The ABEC rating is particularly important in applications requiring high levels of accuracy and performance, such as in aerospace, medical equipment, and precision machinery. By adhering to ABMA standards and the ABEC system, manufacturers and users can ensure bearings meet stringent operational requirements and integrate seamlessly across various industries.

Essential Attributes for Bearing Selection

Selecting the appropriate bearing for an application requires consideration of various attributes, which impact performance, durability, and suitability for specific load or environmental conditions.

Bearing Type

Ball Bearings: The Conrad (or non-slot fill) bearing is the most common design, which omits a filling slot and instead relies on displacing the inner race to load the balls. A cage is used to keep the balls evenly spaced.
Roller Bearings: The choice of roller type—cylindrical, tapered, or spherical—depends on the load requirements, as different types can handle varying degrees of radial and axial loads.
Mounted Bearings: These require an additional style selection (e.g., pillow block, flange) along with the bearing type, such as ball, roller, or spherical.
Linear Bearings: Linear bearings vary from simple ball bearing cages, used in applications like die-post bushings, to recirculating ball designs, which allow balls to move linearly along the shaft and then return to their starting position through built-in channels.

Style

Mounted Units: The style attribute applicable to mounted units defines the housing type, with options including pillow blocks, flanges, and take-up units. These housings provide various mounting options and degrees of support.

Material

Bearing Material: Common materials for ball and roller bearings include specialty steel alloys, certain plastics, and sometimes ceramics for high-temperature or corrosion-resistant applications.
Housing Material: Mounted bearings have additional housing materials available, including metals, plastics, or composites, depending on environmental demands and load capacity.

Seal/Shield

Seals and Shields: Bearings exposed to environmental contaminants can be fitted with seals or shields. Shields offer protection from dirt with minimal friction, while seals provide tighter protection against moisture with increased friction due to shaft-contacting lips. These can be added on both or either side of the bearing.

Race

Radial vs. Angular Contact: Ball-bearing races are typically radial or angular contact. Radial bearings support loads perpendicular to the axis, often in deep-groove configurations, while angular contact bearings are angled to handle axial and radial loads effectively. Cup and cone bearings are common in bicycle applications, where the cones can be adjusted to control play.

Locating

Expandable vs. Non-Expandable: Mounted pillow block units are classified as expandable or non-expandable. In setups requiring multiple pillow block bearings, one is typically designated non-expandable to hold the shaft in place, while an expandable unit accommodates minor shaft growth.

Maximum Static and Dynamic Loads

Load Ratings: Bearings are rated for static and dynamic loads, which dictate their suitability based on operational demands. Static load ratings apply to non-rotating loads, which can cause brinelling (permanent indentations) if excessive. Dynamic load ratings are relevant for rotating applications, as the load is distributed across the races.

Properly considering these attributes when selecting a bearing ensures optimal performance, reliability, and longevity under specific application requirements.

Bearings Buying Guide - SkatePro