Bicycle hubs are the central components of your wheels, connecting the spokes to the axle and allowing the wheel to rotate smoothly. They contain bearings that reduce friction, and they often incorporate mechanisms for braking, shifting gears, or engaging freehubs.
Understanding the Basics
- The Hub Shell: This is the main body of the hub, usually made of aluminum or steel. It holds the bearings, axle, and other internal components.
- Bearings: These are small, round components that allow the axle to rotate smoothly within the hub shell. They typically consist of balls or cylindrical rollers that sit between races.
- Axle: This is the rod that runs through the hub, connecting the wheel to the frame. It is held in place by the hub shell and bearings.
- Spokes: These are the thin metal wires that connect the hub to the rim, providing structural support for the wheel.
Different Types of Hubs
- Standard Hubs: These are the most basic type of hub, with simple bearings and no additional features.
- Freehub Hubs: These hubs allow the wheel to rotate freely when you are not pedaling, but they engage when you do. This is achieved through a mechanism that allows the axle to rotate independently of the cassette.
- Disc Brake Hubs: These hubs have a mounting flange for a disc brake rotor. They are typically found on mountain bikes, road bikes, and other bikes that use disc brakes.
- Internal Gear Hubs: These hubs have gears built into the hub itself, allowing for shifting without the need for a derailleur.
How Hubs Work
- Rotation: When you pedal, the axle rotates within the hub shell. The bearings allow the axle to rotate smoothly with minimal friction.
- Engagement (Freehub Hubs): When you stop pedaling, the freehub mechanism disengages, allowing the wheel to coast freely. When you start pedaling again, the freehub engages, transferring power from the pedals to the rear wheel.
- Braking (Disc Brake Hubs): When you apply the brakes, the brake caliper clamps down on the disc rotor, which is attached to the hub. This creates friction and slows the wheel down.
- Shifting (Internal Gear Hubs): To shift gears, you use a shifter that engages a mechanism inside the hub, changing the gear ratio.
Maintenance and Care
Regular maintenance is crucial for keeping your hubs running smoothly. This includes cleaning and lubricating the bearings, adjusting the axle preload, and checking for wear and tear.
