Bicycle Sprocket Assembly Weight Reduction via Axial Stacking
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Solution Overview
Problem
Bicycle sprocket assemblies with increasing numbers of sprockets for higher gear speeds face challenges in reducing overall weight while maintaining structural integrity and compactness, as existing designs often use heavy materials for strength and multiple sprocket supporting members that increase complexity.
Innovation Solution
A bicycle sprocket assembly configuration featuring a series of sprockets with progressively smaller pitch circles and a reduced number of sprocket supporting members, where sprockets are strategically attached and spaced to minimize weight and maximize compactness, using a combination of fasteners and spacers to maintain axial and rotational alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple sprocket supporting members are used to support a large number of sprockets, then the gear speed range increases, but the overall weight of the assembly increases
Solution Approach 1:
The patent consolidates multiple sprocket supporting members into a single integrated supporting member that can support up to ten sprockets. This merging approach reduces the total weight by eliminating redundant supporting member structures while maintaining the capability to provide a wide gear speed range through the arrangement of multiple sprockets with different pitch circle diameters on the single supporting member.
Solution Approach 2:
The patent arranges sprockets in an axial direction with different pitch circle diameters, utilizing the axial dimension to accommodate multiple sprockets without increasing radial width. This dimensional arrangement allows a single supporting member to effectively support multiple sprockets for various gear speeds, reducing the need for multiple supporting members and thereby reducing overall weight.
2Adaptability or versatility
If multiple sprocket supporting members are used to support more sprockets, then the number of available speeds increases, but the device complexity increases
Solution Approach 1:
The patent integrates the function of multiple sprocket supporting members into a single supporting member structure. This merging simplifies the overall device by reducing the number of separate components, decreasing assembly complexity, and lowering the number of parts that need to be manufactured, maintained, and assembled, while still providing support for multiple sprockets to achieve a high number of available speeds.
Solution Approach 2:
The single sprocket supporting member is designed to perform multiple functions: supporting up to ten sprockets with different pitch circle diameters, providing a wide range of gear speeds, and maintaining structural integrity. This multi-functional design eliminates the need for multiple specialized supporting members, thereby reducing device complexity while increasing the number of available speeds.
3Strength
If heavy steel materials are used for sprockets to provide adequate strength, then the structural integrity is maintained, but the overall weight of the assembly increases
Solution Approach 1:
The patent employs composite material construction where sprockets are made from lightweight materials such as aluminum or other light metals, while the single supporting member is constructed from strong steel or alloy materials. This composite approach allows the sprockets to be lightweight for reduced overall weight, while the strong supporting member provides the necessary structural integrity to support multiple sprockets and withstand operational loads.
4Adaptability or versatility
If sprockets are arranged with larger pitch circle diameters for lower gears, then the gear ratio range increases, but the axial width of the assembly increases
Solution Approach 1:
The patent utilizes the axial dimension to arrange sprockets with different pitch circle diameters, allowing a wide gear ratio range to be achieved without significantly increasing the radial width of the assembly. By stacking sprockets axially on a single supporting member, the design accommodates various gear ratios while maintaining a compact overall structure with controlled axial width.
Data Source
AI summary
A bicycle sprocket assembly is basically provided with a first sprocket having a first pitch circle diameter, a second sprocket having a second pitch circle diameter, a third sprocket having a third pitch circle diameter, a fourth sprocket having a fourth pitch circle diameter, and a sprocket supporting member. At least one of the second and third sprockets is attached to the sprocket supporting member. The first sprocket is attached to the second sprocket so that the second sprocket is positioned between the first sprocket and the sprocket supporting member in an axial direction. The fourth sprocket is attached to the third sprocket so that the third sprocket is positioned between the sprocket supporting member and the fourth sprocket in the axial direction. The second sprocket is adjacent to the third sprocket without another sprocket positioned therebetween in the axial direction.