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The Ultimate Guide to Bicycle Bearings
Bicycle bearings are one of the important parts of a bicycle. Their function is to support and rotate the shaft, and to withstand the impact of the wheel and the ground during movement. As we all know, bicycles are a common means of transportation with complex and diverse structures. The types of bicycle bearings include: pedal bearings, derailleur bearings, wheel hub bearings, bottom bracket bearings, headset bearings, frame bearings, etc. Every bicycle mechanic knows that optimally functioning bearings are critical to the performance of any bike.
Bearings are used in many parts of a bicycle. Through the support of bearings, friction can be greatly reduced, energy loss can be reduced, rotation efficiency can be improved, positioning accuracy can be enhanced, and shaft deflection and vibration can be reduced. Let us understand the location of bicycle bearings.
Headset bearing
The headset bearing is a key component located between the bicycle’s front fork and head tube, responsible for supporting and enabling the bicycle’s steering movement. They can withstand both the force exerted by the rider’s hands and the weight of the front fork, functioning to ensure smooth steering of the bike. Head tube bearings usually consist of a pair of ball bearings or roller bearings installed in appropriate locations within the head tube. Head tube bearings facilitate smooth rotation between the headset and fork, resulting in agile steering and maneuverability of the bike. The head tube bearing is an important part of a road bicycle and has an important impact on the vehicle’s handling and service life. Head tube bearings usually have an inner diameter of 30mm or 40mm and an outer diameter of 41mm or 52mm. The specific model will vary depending on the model and brand of the vehicle.
Frame bearing
The frame bearing is located at the center of the bicycle frame, including the rear axle housing, down tube, rear shock absorber, etc. Frame bearings provide support for the bicycle’s own weight and the rider’s weight and connect different components, making the overall frame structure stable and durable. The type and location of frame bearings may vary depending on the type and design of the bicycle. The frame bearings of road bicycles consist of bottom bracket bearings and steering head bearings. Among them, the bottom bracket bearing usually adopts the imperial specification of 68mm or 73mm, the BB30 specification with an inner diameter of 24mm or 30mm, and the Press Fit specification of 86.5 or 92mm. Steering head bearings usually come in diameter sizes of 1 inch, 1-1/8 inches, and 1-1/4 inches.
Pedal bearing
Pedal bearings are a key component that connects bicycle pedals to the crank arm, allowing the pedals to rotate smoothly during riding and withstand the forces generated when the rider pedals. Commonly used are sealed rolling bearings, which contain small balls or rollers to provide smoother and efficient rotation. Bicycle pedal bearings can reduce frictional resistance and improve rotational stability. Bearing pedals include many types, such as deep groove ball bearing pedals, tapered roller bearing pedals, angular contact ball bearing pedals, etc.
Hub bearing
The wheel hub is the key component that connects the front wheel, rear wheel and bicycle frame. They provide support and allow the bicycle hub to rotate smoothly during turns. Wheel bearings are designed to withstand lateral and longitudinal forces, ensuring the rider maintains stable handling when cornering. The main function of the wheel hub bearing is to reduce friction for rotation and also to transmit force. It bears very large radial load (vehicle weight) and axial load (lateral force or lateral impact force of the tire during steering). Front wheel bearings usually have an inner diameter of 10mm or 12mm and an outer diameter of 28mm or 32mm; rear wheel bearings usually have an inner diameter of 15mm or 17mm and an outer diameter of 28mm or 30mm.
Bottom bracket bearing
The bottom bracket is one of the key drivetrain components of a bicycle, located between the crankset, flywheel, and crank arms. The function of the bottom bracket is to transmit the power generated by the rider’s pedaling to the rear wheel and rotate the rear wheel through the chain. Bottom bracket bearings often use sealed rolling bearings to reduce friction and energy loss, thereby improving cycle efficiency.
Transmission bearing
The derailleur bearings are located inside the bicycle derailleur and are responsible for supporting and ensuring the smooth operation of the derailleur gears. High wear resistance and load-bearing capacity are required to withstand the rider’s frequent shifting needs.
Bearings in various parts of the bicycle play a vital role in providing smooth rotation and movement, maintaining stability and improving riding efficiency. Their design and quality directly affect the performance and comfort of the bike. Therefore, when purchasing and maintaining a bicycle, it is very necessary to understand the functions and characteristics of the bearings of each component. If you have questions about this, please contact Aubearing.
Types of bicycle bearings
Bushings, loose ball, cage ball bearings, needle rollers and ball bearings are the main types of bearings found in bicycle frames and components. Here we explain how each type of bearing differs from the others.
A bushing (also called a sleeve bearing) is a type of plain bearing, a sleeve that sits between two surfaces to reduce friction, and is used in shock mounts, cheaper pulleys, and shifters.
Loose sleeve ball bearings
The proven live ball hub design has lasted for decades and makes the system easy to service. The contact surfaces of the outer and inner rings are machined to a smooth surface to match the contours of loose sleeve ball bearings, which is how they operate. Loose ball bearings are commonly used throughout entry-level bikes, including hubs, bottom brackets, and headset. At the high end of the market, most brands have moved away from loose ball bearings. The ball and retainer system is similar to a loose ball setup, but is less expensive to assemble, making it suitable for entry-level components.
Cage bearing
Loose ball bearings are sometimes secured within a cage, also called a cage (hence the term “cage bearing”). It is usually made of pressed steel and holds loose ball bearings separated from each other. Although cage bearings are often associated with lower-end products, they are not universally bad. Aubearing manufactures cage bearings with excellent performance characteristics.
If you look closely, you can see a row of needle bearings inside the pedals of some high-end bicycles. Needle roller bearings are a type of roller bearing that are relatively uncommon in the bicycle world. The exception is pedals, and the occasional exception in head tubes, but even then they’ve given way to much of the ground being taken over by newer, cheaper technology. In needle roller bearings, the bearing itself is cylindrical, rather than a ball bearing.
Angular contact ball bearings are a type of bicycle bearing with higher stiffness and load-bearing capacity, where the greater the support angle, the greater the stiffness. This type of bearing will produce tension and pressure resistance when the side is stressed, so it is generally used in high-strength parts such as front axles and steering forks. Angular contact bearings require tight tolerances because they are directional. There are internal and external components, and they can be compared in design to old-school cup-and-cone systems. They supplement the radial and lateral force loads exerted by the bicycle’s rotating components, 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 hubs, cranks and suspensions. ,
Tapered roller bearings are also one of the uncommon types of bicycle bearings. They have the advantages of strong load-bearing capacity and stable rotation. They are mainly used in steering forks, rear axles and other parts. The inner and outer rings of this type of bearing have conical surfaces, and the rollers roll between the inner and outer rings to bear the load.
Deep groove ball bearings are one of the common types of bicycle bearings. They are popular than tapered roller bearings and have a wider range of applications, such as front axles, rear axles, automatic transmissions, etc. This type of bearing generally consists of an inner ring, an outer ring, a ball and a cage, with the ball being the main component that bears the load.
Air pressure bearing
Pneumatic bearings are a special type of bicycle bearings that do not require the use of grease or lubricating oil and produce no friction and wear. It uses the pressure of gas to support the load, so it can effectively reduce resistance and increase riding speed. However, due to the difficulty in processing and high manufacturing cost of pneumatic bearings, they are not yet popular.
Bicycle bearing materials
The material used in bicycle bearings determines their durability and corrosion resistance. When making your selection, ensuring you choose a high-quality bearing material is a key factor in ensuring its durability and extending its service life. Based on many years of experience in manufacturing bicycle bearings, Aubearing summarizes the following common bearing materials and their characteristics:
Stainless steel bicycle bearings are known for their excellent anti-rust properties and have excellent water and chemical resistance. This makes stainless steel bicycle bearings suitable for a variety of environments, including wet conditions. The excellent wear resistance and high hardness of stainless steel bicycle bearings allow them to withstand greater loads while extending their service life. Compared with ordinary bearings, stainless steel bearings not only have obvious advantages in materials, but also are much better than ordinary bearings in terms of technology and precision. During the rotation of the bicycle, stainless steel bearings work stably and have low noise.
Ceramic bicycle bearings are typically made from hard ceramic materials (zirconia, silicon nitride, silicon carbide) that offer excellent hardness and wear resistance. Not only is it lightweight, it also offers low friction and high corrosion resistance, making it an excellent choice for high-performance bikes. Its superior low-friction characteristics help achieve higher speeds while maintaining stable and efficient operation. Ceramic bicycle bearings are a popular upgrade for cyclists looking for a efficient and durable ride. It’s worth noting that all-ceramic bicycle porcelain bearings are indeed likely to chip and crack when exposed to a severe enough impact, such as potholes and cracks in the road. Aubearing has been a pioneer in ceramic bearings since 2003. Ceramic bearings are made from materials that are harder and corrosion-resistant than steel bearings, leading to improved performance and longevity.
Bearing steel bicycle bearings
Bearing steel is a cost-effective and affordable bearing material with good strength and durability. Although not as corrosion-resistant as stainless steel and ceramics, bearing steel still provides excellent performance in a variety of conditions. The selection of high-quality bearing steel ensures stable operation under normal riding conditions. Bearings Steel bicycle bearings are one of the best options for the vast majority of people who don’t have enough budget.
Hybrid ceramic bicycle bearings
The hybrid ceramic bearing range covers most applications on bicycles such as head tubes, wheels, hubs, bottom brackets and pedals. Generally speaking, hybrid ceramic bearings have a life expectancy of 2 to 5 times that of steel bearings, but this depends heavily on operating conditions and other factors. Many experienced cyclists and professionals use ceramic hybrid bearings for superior performance. They are known to be much stronger than steel, but at the same time lighter. Hybrid ceramic bearings are made from steel inner and outer rings, PTFE cages, rubber seals and ceramic balls. Hybrid ceramic bearings seek to combine the best of both worlds – corrosion resistance with exceptional strength and speed.
One benefit of hybrid ceramic ball bearings is further reducing the weight of the bike, allowing the rider to climb faster. Another benefit is that due to the lack of grease, there is reduced friction within the bearings, as hybrid ceramic bearings are inherently self-lubricating, allowing for higher rpm and consistent rotation, which can improve your cadence.
When selecting bicycle bearing materials, factors such as riding conditions, expected loads, environment and budget should be considered. Stainless steel and bearing steel are common choices, each with different characteristics that can be selected based on your needs. No matter which material you choose, be sure to choose a high-quality and reputable manufacturer to ensure the durability and longevity of your bearings.
Bicycle bearing seals and shields effectively isolate external dust, moisture and contaminants, reducing wear and damage. Sealing and protection are vital factors when it comes to ensuring the durability and long life of your bicycle bearings. The following are some commonly used bearing sealing and protection methods and their functions and characteristics:
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Metal covers are usually made of stainless steel or bearing steel, which have good corrosion resistance and strength. These covers effectively isolate the ingress of dust, moisture and contaminants, protecting the inside of the bearing from external environmental factors. The advantages of metal covers include durability, allowing them to maintain stability in a variety of harsh conditions.
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Rubber seals are a common sealing method that effectively prevents dust, moisture, and contaminants from penetrating. The rubber seal has excellent elasticity, allowing it to fit tightly in the space between the bearing and the external environment. This sealing method provides excellent protection against contamination and damage to the bearings.
Choosing the right sealing and protection method depends on your riding conditions and environment. If you regularly ride in wet or dusty areas, it’s crucial to choose bearings with effective sealing technology. Likewise, choose appropriate covers and protection methods based on your usage scenarios to ensure stable, long-lasting operation of the bearings in various environments.
Consider load and proper lubrication
The load a bearing is subjected to affects its service life. Make sure the selected bearings can handle the expected loads to avoid excessive damage. Additionally, regular lubrication is crucial. Choosing the right lubricant can ensure the smooth operation and durability of the bearing.
Regular maintenance and inspection
Regular maintenance and inspection of bicycle bearings can help detect problems early and take appropriate action. Ensuring bearings are in good condition can reduce unnecessary damage and replacement.
Bicycle bearing grades
You will typically see bearings called “ABEC“. Followed by a number (for example, ABEC 1, 3, 5, 7, and 9). Simply put, the higher the number, the higher quality the bearing. It acts as a rough “good, better, best ranking”. ABEC standards define bore diameter (acceptable variation in inner bearing bore size), parallelism (variation in width), and radial raceway runout (variation in the groove in which the ball sits). However, ABEC systems give up load handling, ball accuracy, or Rockwell hardness (material hardness). When it comes to bikes, the material is much important than the ABEC grade, and for most applications, ABEC 3 and 5 are perfectly suitable for all uses on the bike. As for ABEC levels 7 and 9, this level of accuracy is suitable for equipment that rotates thousands or hundreds of thousands of times per minute, which is a bit of a luxury for riding.
Durability and longevity are key considerations when choosing bicycle bearings. By choosing high-quality materials, superior sealing technology, proper loading and lubrication, and regular maintenance and inspections, you can ensure that the bearings you choose maintain excellent performance over the long haul. Choosing Aubearing, a reliable manufacturer, allows you to enjoy a smoother, reliable riding experience.