Types of Rear Hubs

In the context of bicycles, the rear hub is a critical component of the wheel that allows it to spin freely while providing support and stability. It is the central part of the wheel, connecting it to the frame of the bike and allowing the rear wheel to turn. The rear hub also houses the cassette or freewheel, which provides the gearing system for the bike.

There are various types of rear hubs, each designed for different uses and requirements. Here are some of the most common ones:

Freewheel Hub: This is the most common type of rear hub found on many bicycles, especially older models. It features a threaded freewheel mechanism that screws onto the hub. The freewheel contains the ratchet mechanism and cogs that connect the rear wheel to the drivetrain. Freewheel hubs are generally simpler and less expensive than other systems but can be heavier and less efficient.
Freehub Hub: Modern bikes often use the freehub rear hub, which is more advanced and offers better performance than the older freewheel design. The freehub body is a part of the hub axle, and the cassette of gears is mounted directly onto it. This system eliminates the need for a separate freewheel, reducing weight and increasing strength. Freehub rear hubs also provide better power transfer and are more efficient than freewheel hubs.
Track Hub: Track hubs are designed specifically for fixed-gear bicycles used on velodromes or tracks. These hubs do not have a freewheel mechanism; the rear hub is fixed directly to the axle, meaning the rear wheel must always turn with the pedals, creating a direct drive system. Track hubs are built for high-performance cycling and are optimized for speed and power transfer. They are generally lighter and stiffer than other hubs, offering less flex and better acceleration.
Disc Brake Hub: Disc brake hubs are designed to accommodate disc brakes, which offer better stopping power and performance than traditional rim brakes. These hubs have mounting points for the disc rotor, which is attached to the hub. Disc brake hubs are available in both freewheel and freehub designs and are commonly used on mountain bikes and high-performance road bikes. They provide improved braking performance, especially in wet and muddy conditions, and offer more consistent stopping power than rim brakes.

Scenarios of Rear Hubs

Understanding the various scenarios where a rear hub is used can help businesses appreciate the different demands and requirements that may exist. Here are some key scenarios:

Urban Commuting

Rear hubs are essential to the bicycle's functionality, allowing people to navigate the busy streets of their communities. Bicycles with the right hubs and freewheel mechanisms enable smooth and reliable rides. People can ride through traffic and intersections with minimal noise and disruption.
Mountain Biking

Rear hubs are designed to handle the increased stress of off-road biking. The larger bearings and more robust construction of the hubs ensure that they can withstand the impact of rough terrain. This will reduce the likelihood of the hubs bending or breaking, which would cause the wheels to go out of true, resulting in a rough ride.
Road Racing

Quality rear hubs are crucial when participating in competitive racing. Lightweight hubs reduce the overall weight of the bicycle, enabling the rider to go faster. Additionally, the rider's ability to accelerate quickly is improved by the freehub mechanism's quick engagement.
Touring

Reliability and durability are critical when riding long distances, as in bicycle touring. Rear hubs are constructed to be long-lasting and require little maintenance, making them ideal for riders who travel great distances and often ride through various environments.
Freestyle BMX

Rear hubs are integral to performing tricks and jumps. The increased strength of the hubs can handle the increased stress of landings. Additionally, the hub's freewheel mechanism allows riders to pedal backward when performing tricks.
Electric Bicycles

Electric bicycles require specific rear hubs to accommodate the electric motor. These hubs are designed to handle the increased torque from the motor, providing a smooth and efficient ride. Additionally, the motor-integrated hubs ensure that the bicycle remains lightweight and easy to maneuver.

How to choose a rear hub

Choosing the correct rear hub is critical for building a bicycle that performs well and is dependable. Here are some things to think about when picking a rear hub:

Bike Type

The kind of bike being constructed or modified greatly influences the choice of rear hub. Every bike category requires a specific rear hub to function optimally. For instance, mountain bikes require robust hubs that can handle off-road abuse. At the same time, road bikes need hubs built for speed and efficiency. Single-speed and fixed-gear bikes need straightforward, lightweight hubs.
Hub Standard

Another important factor to consider is the rear hub's compatibility with the bike frame. The hub spacing and axle type must match the bike frame's specifications to ensure a proper fit. Common spacing measurements for road bikes are 130mm for road bikes and 135mm for mountain bikes. Thru-axles and quick releases are the main axle types, each with unique benefits.
Driver Type

The driver type is another important consideration when selecting a rear hub. The driver is the part of the hub that the cassette attaches to. It needs to be compatible with the specific type of cassette used, which varies depending on the bike and rider's preferences. Most rear hubs use either Shimano, SRAM, or Campagnolo drivers. Shimano and SRAM drivers are similar, making it easier to choose between them. However, Campagnolo drivers offer better quality and are more durable than the rest.
Durability and Maintenance

Durability and maintenance frequency are also important factors when selecting a rear hub. Hubs need regular maintenance, like cleaning and re-lubrication, to perform well and last long. However, some hubs offer sealed bearings that protect them from dirt and moisture, reducing maintenance needs. Selecting a hub with an appropriate balance of durability and maintenance requirements is essential for reliable performance.

Functions, Features and Design of Rear Hub(Combined)

The rear hub is available in various designs, functions, and features. This is because bikes are made for different purposes, and their needs will differ from one bike to another. Here are some common features, functions, and designs of a bicycle rear hub:

Shell Material

Rear hubs can be made from various materials, such as aluminum, steel, magnesium, carbon fiber, and titanium. Every material has its advantages and disadvantages. For instance, aluminum is lightweight and offers good strength. On the other hand, carbon fiber has the advantage of being lightweight but is expensive.
Shell Design

Hubs can have different shell designs depending on the bike type and usage. For instance, road bikes may have aerodynamically designed shells to reduce drag, while mountain bikes may have more robust shells to endure rough terrain.
Axle Type

The type of axle on a hub can play a significant role in its performance and durability. Hubs can have different axle types, such as quick-release and thru-axle. Quick-release axles allow for easy wheel removal and installation, while thru-axles provide increased stiffness and stability, especially on bikes with disc brakes.
Seal Design

Rear hubs can have different seal designs that help keep dirt and moisture out of the hub to maintain smooth operation and extend the hub's lifespan. Some hubs have simple seals, while others have more complex sealing systems.
Freehub Mechanism

Freehub systems are designed differently to suit various cycling needs. For instance, some may engage more quickly, benefiting cyclists who accelerate frequently, while others might offer smoother operation.
Braking System

Hubs can be designed for different braking systems, such as disc or rim brakes. Disc brake hubs have a mounting point for the disc rotor, while rim brake hubs do not need a mounting point since the braking surface is on the wheel's rim.
Paint and Finish

Rear hubs can have different finishes and paints. Some may have anodized coatings for added durability and a high-quality appearance, while others might have powder-coated finishes for enhanced protection and aesthetic appeal.

Q&A

Q: What is the function of the rear hub?

A: The rear hub is a crucial component of a bicycle wheel. It serves several important functions:

- It houses the bearings, which allow the wheel to spin smoothly around the axle.

- It provides attachment points for the spokes, connecting the wheel to the rear wheel assembly.

- It contains the freehub or freewheel mechanism, which allows the rider to coast without pedaling while still providing drive to the wheel when pedaling.

- Some rear hubs also provide mounting points for disc brakes and the cassette for multi-gear bicycles.

Q: How often should rear hubs be maintained?

A: The frequency of rear hub maintenance can vary depending on several factors, such as how often and how intensely a bicycle is used, the riding conditions, and the type of rear hub. Generally, it is recommended to perform basic maintenance, such as cleaning and lubricating, every six months or so. However, more intensive servicing, including bearing replacement, should be done every one to two years, especially if the hub is subjected to harsh conditions or regular heavy use.

Q: Can a bicycle rear hub affect gear shifting?

A: Yes, a bicycle's rear hub can significantly affect gear shifting. The rear hub houses the components that interact with the bike's gearing system. If the hub is not properly maintained or if its parts are worn out or damaged, it can lead to poor gear shifting. For instance, a worn-out freehub body may cause skipping or hesitation when engaging the pawls. Additionally, dirt and lack of lubrication can affect the mechanics of the rear hub, leading to sluggish or noisy shifting. Regular maintenance ensures the hub and its components function smoothly, resulting in precise and reliable gear shifting.