Wear-Resistant 40Cr Planetary 3-Speed Bicycle Gear Set for Internal Hub Shifting

Product Specification

Wear-Resistant 40Cr Planetary 3-Speed Bicycle Gear Set for Internal Hub Shifting Systems

3‑speed bicycle gears are core transmission parts for internal 3‑speed bicycle shifting systems, including drive gear, planetary gear, internal ring gear, sun gear, ratchet gear and shifting gear. They fit Japanese‑style internal 3‑speed hubs, domestic internal 3‑speed hubs, folding bikes, urban commuter bikes and senior bikes. Made of 45# steel, 40Cr and powder metallurgy, processed by precision stamping, hobbing, induction hardening and carburizing, they feature compact structure, stable transmission, wear resistance, impact resistance, rust‑proof and maintenance‑free. The planetary gear structure realizes 3‑speed shifting (low/medium/high speed). Torque adjustment is completed by internal hub gear meshing for labor‑saving climbing, steady cruising and high‑speed riding, widely used in commuter bikes, folding bikes and leisure bicycles.

Product Features

• Planetary 3‑speed structure: Sun gear + planetary gear + ring gear realize 3‑stage precise shifting with smooth gear change.
• High wear resistance & strength: Induction‑hardened teeth with HRC 48–56 hardness resist wear and chipping under long‑term riding.
• Compact & miniaturized: Fully integrated inside the hub, dust‑proof and water‑proof for harsh urban commuting environments.
• Quiet transmission: Precision tooth profile with uniform meshing clearance ensures low‑noise riding.
• Rust & corrosion resistance: Blackening or galvanizing resists rain, mud and humidity to avoid rust and jamming.
• Lightweight: Powder‑metallurgy thin‑type gear design reduces overall bike weight for easier riding.
• Strong interchangeability: Compatible with Shimano, Novatec and domestic universal internal 3‑speed hubs for easy replacement.
• Maintenance‑free long life: Sealed lubrication structure requires little daily maintenance with long service life.

Technical Parameter Table

Working Principle

• Low speed: Ring gear fixed, sun gear input power, planet carrier output, reducing speed and increasing torque for climbing and load‑carrying.
• Medium speed: Sun gear, carrier and ring gear rotate synchronously at 1:1 ratio for steady flat‑road riding.
• High speed: Sun gear fixed, ring gear input power, carrier outputs accelerated speed for downhill and fast riding.
• Shifting control: Shift cable pulls pawls to switch gear locking status for 3‑speed selection.
• One‑way ratchet drive: Ratchet gear enables one‑way transmission and freewheeling without pedal reverse rotation.

Main Applications

• Complete shifting gear sets (sun, planetary, ring gear) for rear hubs of internal 3‑speed bikes.
• Shifting systems for urban commuter bikes, folding bikes, senior bikes and leisure bicycles.
• Replacement gear parts for Shimano and domestic internal 3‑speed hubs.
• Low‑speed 3‑speed shifting mechanisms for electric‑assist bicycles.
• 3‑speed transmission gears for small tricycles and kids’ assist bikes.
• Matching gear components for exported internal 3‑speed bicycles.

Product Advantages

• Accurate 3‑speed switching: Stable planetary shifting with clear gear changes, no slipping or jamming.
• Long wear‑resistant life: Hardened tooth surface resists riding impact with twice the life of ordinary gears.
• Sealed dust‑proof & water‑proof: Integrated inside hub, resisting rain and mud with good rust resistance.
• Lightweight & labor‑saving: Compact lightweight gears reduce overall riding resistance.
• Maintenance‑free design: Permanent internal grease lubrication with no regular maintenance required.
• Strong versatility: Compatible with most internal 3‑speed hubs for simple replacement.
• Quiet & smooth: Precision tooth profile delivers smooth meshing and low noise.
• Cost‑effective: Graded material options cover household, export and maintenance scenarios.

Why Choose us?

• 7-axis CNC Grinding: We adopt high-precision 7-axis CNC grinding machines, holding tolerances as tight as ±5μm, ensuring gears run quietly, smoothly and with outstanding durability.
• Strong technical expertise: Our core R&D team includes doctoral and master’s professionals specializing in spiral bevel gear technology, providing strong technical support for complex projects.
• Rigorous testing & high precision: All gears undergo 100% inspection with Gleason metrology systems. We can achieve DIN 6 grade accuracy with strict control over tooth profile and direction errors, keeping our quality at the industry-leading level.
• High transmission efficiency: Our gear designs support a single-stage reduction ratio of up to 300:1, with actual transmission efficiency reaching over 95%, greatly improving energy utilization.
• Excellent durability & cost efficiency: Our gears deliver 40% lower lifecycle cost and a failure rate below 0.5%, ensuring stable long-term operation and reduced maintenance costs.
• Fast response & short lead time: Supported by our digitalized production process, we are able to shorten the delivery cycle to only 20 working days, helping you accelerate project development and launch.
• Professional custom design capability: We provide fully customized gear solutions for applications requiring high-reduction, high-speed, heavy-load, low-noise, and special small-tooth profiles, based on your actual working conditions.