Six Core Systems of a Bicycle

1. Frame System (Main structure of the bicycle)

Parts: Frame, front fork, headset, seat post, derailleur hanger, bottom bracket

Function: Supports all components and determines the structure and overall strength of the bike.

1. Frame
   The main body of the bike, connecting all components together.
2. Front fork
   Installed at the front frame, holds the front wheel and works with the headset for steering.
3. Headset
   A set of bearings inside the head tube, enabling flexible turning of the front fork and handlebars.
4. Seat post
   A tube inserted into the frame to mount and adjust the height of the saddle.
5. Derailleur hanger
   An extension on the rear frame for mounting the rear derailleur; it is a fragile replaceable part.
6. Bottom bracket
   The bearing unit at the frame bottom, connecting the crankset and allowing the pedals to rotate smoothly.

2. Steering & Control System

Parts: Handlebar, stem, grip, brake lever, shift lever, bell

Function: Controls riding direction, braking and gear shifting.

1. Handlebar: The main part for riders to hold and steer the bike.
2. Grip: Mounted on both ends of the handlebar for anti-slip and comfortable holding.
3. Stem: Connects the head tube and handlebar to fix their positions.
4. Brake lever: Operates the brake to slow down or stop the bicycle.
5. Shift lever: Adjusts gears to change the transmission ratio.
6. Bell: Used to warn pedestrians and other riders while cycling.

3. Wheel System

Parts: Rim, inner tube, tire, spoke, front hub & rear hub

Function: Bears the weight of the bike, enables rolling movement and absorbs road vibrations.

1. Rim: The circular frame that holds the tire.
2. Inner tube: An inflatable tube that maintains tire pressure.
3. Tire: The outer rubber part contacting the ground, featuring wear resistance and good grip.
4. Spoke: Connects the hub and rim to bear and distribute pressure.
5. Front hub & rear hub: The core rotating components of the wheel set.

4. Drivetrain System

Parts: Pedal, crank, chainring, bottom bracket, chain, cassette, front derailleur, rear derailleur

Function: Transmits pedaling power to the rear wheel to propel the bicycle and realize gear adjustment.

1. Pedal: Where riders place feet to apply force.
2. Crank: Connects pedals and chainring to transmit power.
3. Chainring: Front gear disc that works with the chain.
4. Bottom bracket: Bearing assembly for the crank to rotate smoothly.
5. Chain: Transmits power from chainring to cassette.
6. Cassette: Rear gear set for gear shifting.
7. Front derailleur: Shifts the chain between different chainrings.
8. Rear derailleur: Adjusts the chain position on the cassette.

5. Brake System

• Rim Brake: Brake caliper, brake cable, brake pad
• Disc Brake: Brake caliper, brake rotor, brake pad, hydraulic hose / brake cable

Function: Slows down or stops the bicycle to ensure riding safety.

1. Brake caliper: Clamps the brake pad to create friction for braking.
2. Brake cable: Transmits force from the brake lever to the caliper.
3. Brake pad: Creates friction to decelerate the bike.
4. Brake rotor: The metal disc matched with disc brakes.
5. Hydraulic hose: Delivers hydraulic pressure for hydraulic disc brakes.

6. Saddle & Accessory System

Parts: Saddle, quick release, fender, rear rack, kickstand, etc.

Function: Enhances riding comfort and practicality.

1. derailleur hanger: Also known as gear hanger, a vulnerable spare part.
2. headset: The bearing assembly for steering at the head tube.
3. cassette: Gear cluster mounted on the rear wheel.
4. brake rotor: Brake disc.
5. brake pad: Brake shoe. Used for disc brakes and rim brakes respectively.
6. quick release: A mechanism for fast installation and removal of wheels and seat posts.

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