Complete Parts List & Function Introduction for Electric Assist Bicycle (E-Bike)

1. Electric Drive System (Core Power)

1. Motor — Power Source

  • Mid-drive Motor

    Installed at the frame bottom bracket. Low center of gravity, stable handling, compatible with transmission gears, strong climbing performance and high efficiency; mostly used for mid-to-high-end models.

  • Hub Motor

    Embedded in the rear (or front) wheel hub. Simple structure, easy maintenance, low cost; center of gravity slightly rearward, lower climbing efficiency; widely used for urban commuter bikes.

2. Battery — Energy Core

  • Type: Mainstream Lithium Battery — lightweight, high energy density, long service life; a few entry-level models use lead-acid batteries.
  • Parameters: Voltage (36V/48V/52V), capacity (10Ah–20Ah), energy (360Wh–1000Wh), directly determine range and power output.
  • Installation: Down-tube built-in, rear rack mounted, vertical tube hidden design; mostly detachable for convenient charging and anti-theft.

3. Controller — Vehicle Brain

Receives signals from sensors, throttle and display; precisely regulates motor output (torque/speed); protects battery and motor; realizes assist level switching, speed limit, over-current/over-voltage/overheating protection.

Usually hidden inside the frame down tube, battery compartment or inner side of rear rack.

4. Sensors — Perception & Linkage

  • Torque Sensor: Detects pedaling force; higher force brings stronger assist, smooth and natural riding feeling, standard for high-end models.
  • Cadence Sensor: Only detects pedal rotation, provides fixed-ratio assist; low cost but rigid assist, common for entry-level bikes.
  • Brake Cut-off Sensor: Cuts off motor power instantly when braking to avoid dragging and improve safety.
  • Hall Sensor: Feeds back motor internal position to ensure smooth start and efficient operation.

5. Display / Control Panel — Human-Machine Interaction

Real-time display of speed, battery level, mileage, assist level, fault code; supports Eco/Standard/Power mode switching, brightness adjustment, and Bluetooth connection (high-end versions).

Equipped with LCD/LED screen and handlebar integrated buttons; some with USB charging port.

6. Throttle (Optional) — Full Electric Drive

Twist-grip / thumb button type; runs the motor without pedaling, suitable for starting, climbing or non-pedal riding (restricted by traffic regulations in some regions).

2. Frame & Structural Parts (Load-Bearing Base)

1. Frame — Main Skeleton

  • Material: Aluminum Alloy (mainstream, lightweight & tough), Carbon Fiber (high-end, lightweight & shock-absorbing), Steel (entry-level, heavy but low cost).
  • Design: Reserved mounting positions for battery and motor; reinforced bottom bracket and rear chainstay to bear motor torque and extra weight.

2. Front Fork

  • Rigid Fork: Lightweight, no shock absorption, for flat urban roads.
  • Suspension Fork: Spring/air pressure structure, cushions bumps and improves comfort; used for mountain and commuter bikes.

3. Saddle / Seat Post / Seat Post Clamp

  • Saddle: Wide breathable design for long-distance riding comfort.
  • Seat Post: Aluminum alloy/carbon fiber; shock-absorbing seat post optional for better comfort.
  • Seat Post Clamp: Fastens the seat post for height adjustment.

4. Handlebar / Stem / Grips

  • Handlebar: Flat bar (urban), Riser bar (mountain), Drop bar (road); determines riding posture.
  • Stem: Connects head tube and handlebar, adjusts height and length.
  • Grips: Non-slip rubber/sponge for comfortable holding.

3. Transmission System (Power Transmission)

1. Crank / Chainring

  • Crank: Connects pedal and bottom bracket to transmit pedaling force.
  • Chainring: Integrated with mid-drive motor or independent design; drives chain transmission; tooth count affects gear ratio.

2. Chain

Reinforced thickened design, withstands high motor torque, rust-proof and wear-resistant.

3. Rear Cassette / Sprocket

Multi-gear set (7–11 speed); cooperates with rear derailleur for gear shifting, adapts to different road conditions and slopes.

4. Front & Rear Derailleur

Gear shifting actuator; switches the chain between different cassette/chainring positions to realize gear change; mechanical cable type and electronic shifting (high-end).

5. Shifter

Mounted on handlebar, controls front/rear derailleur for precise gear shifting.

4. Braking System (Safety Guarantee)

1. Brake Types

  • Hydraulic Disc Brake (Mainstream): Strong and linear braking power, stable performance in rainy days, good heat dissipation; standard for mid-to-high-end models.
  • Mechanical Disc Brake: Cable-driven, easy maintenance and low cost, slightly weaker braking force.
  • V-Brake (Rim Brake): Lightweight and low cost; obvious braking attenuation in rainy days; used for entry-level/retro bikes.

2. Brake Lever

Built-in power-off switch; cuts off motor power synchronously while braking for higher safety.

3. Brake Rotor

Stainless steel/aluminum alloy material; size 160mm–180mm; larger size brings better heat dissipation and braking performance.

5. Wheel Set & Tires (Running Parts)

1. Rim

  • Material: Aluminum Alloy (mainstream, lightweight & impact-resistant), Carbon Fiber (high-end, lightweight & aerodynamic).
  • Size: 26”/27.5”/29” (mountain), 700C (road/commuter).

2. Hub

  • Rear Hub: Integrated with hub motor or cassette mounting position, core for transmission and load bearing.
  • Front Hub: Ordinary bearing hub or built-in speed sensor.

3. Spokes

Stainless steel material; connects rim and hub, bears impact and maintains wheel set rigidity.

4. Tire

  • Urban Tire: Smooth low rolling resistance, wear and puncture resistant, for paved roads.
  • Mountain Tire: Deep rugged tread, strong grip and shock absorption, for unpaved roads.
  • Puncture-proof Thickened Tire: Top choice for daily commuting, reduces flat tire risk.

6. Auxiliary Accessories (Practical & Regulatory)

1. Lighting System (Mandatory for Compliance)

  • Front Light: High-brightness LED (300–1000 lumens), for illumination and warning.
  • Rear Light: Red LED, steady/flashing when braking, improves night visibility.
  • Reflectors: Standard front/rear/left/right installation for passive safety.

2. Fenders

Metal/plastic material, blocks mud and water splashing, essential for rainy day commuting.

3. Rear / Front Rack

  • Rear Rack: Load capacity 5kg–25kg, compatible with rear bags and luggage; some integrated with battery compartment.
  • Front Rack: Light load design for urban shopping.

4. Pedals

Metal/nylon material; non-slip platform design for efficient pedaling; some with built-in reflectors.

5. Bell / Horn

Audible warning device, mandatory for urban riding compliance.

6. Charger

Special lithium battery charger: 42V / 54.6V (for 36V / 48V battery); built-in overcharge/over-current protection, auto-stop when fully charged.

7. Core Differences Between E-Bike & Regular Bicycle

  1. Extra electric drive assembly: Motor, battery, controller, sensors, display — realizes human + electric dual power drive.
  2. Reinforced frame & transmission: Strengthened bottom bracket, thickened chain, optimized center of gravity to adapt to motor torque and extra weight.
  3. Upgraded braking: Standard hydraulic disc brake + brake power-off design to cope with higher speed and vehicle weight.