Asymmetrical Bicycle Roller Chain Plates for Multi-Sprocket Guidance

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Solution Overview

Problem

Conventional roller chains for bicycles face issues with increased loads due to reduced dimensions, leading to incorrect assembly and poor guidance on sprockets, especially with the increasing number of sprockets on the rear wheel hub, which results in malfunctions and wear.

Innovation Solution

The design incorporates asymmetrical chain plates with distinct outer contours to clearly differentiate between the inside and outside of the chain ring, maintaining loaded cross-sections and increasing the distance between chain plates to improve load distribution and guidance, ensuring correct assembly and reduced wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the dimensions of chain components are reduced to adapt to sprockets with smaller axial distances, then the chain can accommodate more sprockets on the rear wheel hub, but the load-bearing capacity of the chain components decreases

Engineering Contradiction:
Improveadaptability to multi-sprocket configurationsVSAvoidload-bearing capacity of chain components
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The chain plate is designed with an asymmetric outer contour where the distance from the longitudinal axis to the outer contour on the guide side is greater than on the engagement side. This asymmetry allows the chain to maintain adequate load-bearing cross-sections while reducing the overall width to fit between closely spaced sprockets. The guide side extends further to provide guidance, while the engagement side remains compact for strength.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

Different regions of the chain plate are designed with different dimensions to fulfill specific functions. The guide side has a larger distance from the longitudinal axis to provide guidance on the sprocket, while the engagement side maintains sufficient cross-section for load bearing. This local differentiation allows the chain to accommodate reduced dimensions overall while preserving critical load-bearing areas.

Inventive Principle:
Principle #3Local quality

2Ease of manufacture

If conventional symmetrical chain plates are used, then manufacturing is simpler, but incorrect assembly occurs and chain guidance on sprockets is poor

Engineering Contradiction:
Improvesimplicity of chain plate manufacturingVSAvoidcorrect assembly and proper chain guidance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The asymmetric outer contour of the chain plate serves as a built-in assembly guide. The guide side with the greater distance from the longitudinal axis must be positioned on the outer side of the chain ring, while the engagement side with the smaller distance is positioned on the inner side. This asymmetry prevents incorrect assembly and ensures proper chain guidance on the sprocket teeth without requiring additional manufacturing complexity.

Inventive Principle:
Principle #4Asymmetry

Data Source

PatentEP3318335B1Roller chain for bicycles
Publication Date: 2023.11.29 SRAM
  • EP3318335B1 patent drawingFigure 1~2
  • EP3318335B1 patent drawingFigure 3~4
  • EP3318335B1 patent drawingFigure 5

AI summary

The invention relates to asymmetrical chain plates for a roller chain for bicycles, which are advantageously suited for use with a reduced chain width on chain drives with a high number of gears. The necessary orientation of the side of the chain with the modified outer contour of the plates to the inside of the chain strand formed by joining the ends to form a chainring is easily achieved due to the readily distinguishable sides of the outer contours of the plates. The chain plates on the inside of the chainring are designed in a known manner for engagement with the teeth of the rear sprockets and the front chainrings, while the chain plates on the outside of the chainring are designed for interaction with the chain guide roller on the rear derailleur.