introduction

Wheel bearings are small precision ball or roller bearings that are pressed or sealed into the center of bicycle wheels. They consist of an inner and outer raceway made of hardened steel with many small steel balls or cylindrical rollers in between. This bearing design reduces friction between the stationary outer ring and the rotating inner ring.

The main purpose of wheel bearings is to allow the hub and attached wheel to rotate effortlessly around the fixed axle. They absorb the radial and axial loads caused by pedaling and braking forces.

Compared to a rubbing surface, bearings produce very low rolling resistance. By using steel balls or rollers and races, bearings make the bike more efficient by minimizing rotational losses. They also dampen small shocks and vibrations, ensuring a smooth ride.

What is a ball bearing? 

Ball bearings are mechanical components that are designed in such a way that the bearing rings are separated by spherical rolling elements. These bearings use the rolling motion of the balls to support axial and radial loads. The main components of a ball bearing include an inner ring (labeled A on the left in Figure 3), an outer ring (labeled A on the right in Figure 3), balls (labeled C in Figure 3), and a cage (labeled B in Figure 3). , which prevents the balls from coming into contact with each other. They are commonly used in high-speed applications such as electric motors and gearboxes. You can find out more about ball bearings in our article about ball bearings at a glance.

Ball bearing components: inner and outer rings (A), cages (B) and balls (C). Credit from: tameson

What is a roller bearing?

Roller bearings, also known as rolling bearings, work on the same principle as ball bearings by efficiently supporting loads while minimizing friction. The difference lies in their shape and construction. While ball bearings use spherical balls, roller bearings use cylindrical rollers that can be cross-shaped or linear.

These bearings with roller elements can be single or double row, with double row bearings being particularly good at carrying radial loads. Available in a variety of shapes and sizes, their versatility allows them to transmit radial and axial loads with minimal friction, making them a valuable component in a variety of applications.

Roller bearings are designed with cylindrical or barrel-shaped rolling elements that provide a larger contact area with the raceway to support heavy radial loads.

Roller bearings have cylindrical, barrel-shaped rolling elements. Credit from: tameson

bearing dimensioning

If you need to replace your ball bearings, it is important to know how to size them correctly. To do this you need to know the ball diameter, which can be measured with an inch caliper for loose ball bearings. Common sizes are 5/32" for headsets and pedals, 3/16" for front wheel hubs and 1/4" for rear wheel hubs and bottom brackets.

For cartridge bearings (sealed bearings), it is particularly important to know three key dimensions: the outside diameter, the inside diameter (bore), and the width. These dimensions, often printed on the bearing itself, are crucial to finding the right replacement part. If these markings are not present, a vernier can be used to measure. A bearing measuring 30x42x7mm should fit e.g. SRAM/Truvative cranks in a BB30 bottom bracket. Additional markings such as 6806 2RS can also help with sizing. If you come across similar numbers, a quick online search should provide the necessary sizing information.

Credit from: rs-online

Stocked materials

The choice of material for bicycle bearings is crucial to their performance. Different materials can affect bearing life, ease of movement and corrosion resistance. Using high-quality materials such as ceramic or stainless steel can extend bearing life and reduce friction, resulting in more efficient driving. In addition, suitable bearing materials can prevent wear and damage, extending the overall life of the bicycle system.

Ceramic bearings

Ceramic bearings have become very popular in cycling due to their exceptional properties. They are known for their high strength, hardness and low coefficient of friction. These features improve speed stability, reduce energy loss and increase efficiency. Ceramic bearings minimize vibration and resonance, providing quieter and more stable operation, especially at high speeds. Additionally, their corrosion resistance ensures long-lasting performance, making them an excellent choice for cyclists who ride in wet or corrosive environments.

chrome steel bearings

Due to their reliable performance, chrome steel bearings are a popular choice for bicycle components. They are robust and durable and can withstand the stress and forces that occur when cycling. Although they have slightly higher friction than ceramic bearings, steel bearings still provide satisfactory speed stability. Cyclists often choose steel bearings due to cost, making them a practical choice.

Hybrid Stock

Hybrid bearings are a type of bearing that uses both ceramic and steel materials. They are equipped with ceramic rolling elements and steel raceways. By integrating ceramic rolling elements, hybrid bearings offer better speed stability compared to pure steel bearings. The ceramic components reduce friction and heat generation, improving speed stability, while the steel races provide the necessary strength and rigidity for stable operation. Hybrid bearings are particularly beneficial in high-speed applications that require a balance between performance and cost.

maintenance of bearings

Before a bearing is removed for inspection, it is important to document its condition and take photos. After checking the remaining lubricant and taking a sample for examination, the cleaning process should be carried out.

A dirty bearing should be cleaned using two cleaning methods, e.g. B. with a rough cleaning and a fine cleaning.

During fine cleaning, the bearings should be carefully cleaned by slowly turning them in cleaning oil.

The bearings are normally cleaned with a neutral, water-free light oil or kerosene. If necessary, a warm alkaline solution can also be used. Before cleaning, it is important to filter the oil to ensure it stays clean. After the cleaning process, the bearings must be lubricated immediately with anti-corrosion oil or anti-rust grease.

Brand Recommend

Shimano
Shimano is the industry's standard original equipment manufacturer with a wide range of models to suit every budget. From the affordable Alivio to the high-quality Dura-Ace, you get legendary Shimano quality assurance. Precise technology ensures consistent spin - for a lifetime. As the inventor of common bearing types such as 6803, their specifications have been proven to simply work.

CeramicSpeed
CeramicSpeed ​​bearings are designed for those who want only a small increase in performance or who work in demanding conditions. The flagship UltrALite uses a ceramic ball design that is 40% lighter than steel. This saves rotational mass for faster acceleration and lower friction for more efficient power transfer. The fully sealed cartridge also simplifies cleaning and relubrication. It is expensive, but racers value the maximum efficiency.

Enduro
Want to increase performance without breaking the bank? The Enduro bearings impress with their intelligent design. Sealed construction protects against water contamination without the need for disassembly. The smooth-running, rust-proof components last a long time and are still affordable. The package includes races and seals for easy installation, saving you additional parts costs. An affordable choice, Enduro offers a noticeable improvement over worn OEM bearings.