Bicycle Rear Sprocket Odd-Even Shifting Configuration
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Solution Overview
Problem
Existing bicycle rear sprocket assemblies face challenges in achieving smooth and reliable shifting, particularly when dealing with even-numbered tooth configurations and multiple shifting facilitation areas, which can lead to inefficiencies in upshifting and downshifting operations.
Innovation Solution
The bicycle rear sprocket assembly incorporates a unique tooth configuration with specific shifting initiation teeth, circumferential areas, and chain-supporting teeth, allowing for even-numbered tooth counts and multiple shifting facilitation areas to facilitate smooth shifting operations by optimizing the engagement of bicycle chain link plates and reducing interference during shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bicycle sprocket uses an even-numbered tooth configuration with multiple shifting facilitation areas, then the sprocket can provide smoother shifting in certain conditions, but it may fail to reliably complete shifting operations due to interference between chain link plates and sprocket teeth
Solution Approach 1:
The sprocket tooth configuration is segmented into specific functional zones: first and second shifting facilitation areas with corresponding shifting initiation teeth, and first and second chain-supporting teeth positioned at specific circumferential locations. This segmentation allows different teeth to serve specialized functions - some optimized for initiating shifts in different directions, others for supporting the chain during transition - thereby resolving the conflict between shifting smoothness and reliable completion
Solution Approach 2:
Different teeth on the sprocket are given different local qualities and positions: shifting initiation teeth are located at specific angular positions within shifting facilitation areas, while chain-supporting teeth are positioned at different circumferential locations to support the chain during upshifting and downshifting. This local differentiation ensures that each tooth performs its specific function optimally, preventing interference and ensuring reliable shifting completion
2Reliability
If the sprocket is designed with specific circumferential area distributions for shifting initiation teeth and chain-supporting teeth, then shifting operations can be reliably completed, but the device complexity increases due to the intricate tooth configuration requirements
Solution Approach 1:
The sprocket circumference is divided into distinct segments with specific functional assignments: shifting facilitation areas containing shifting initiation teeth, and other circumferential areas containing chain-supporting teeth. This segmentation creates a systematic framework that, while detailed, provides a clear design methodology that can be applied consistently across different sprocket sizes and tooth counts, thereby managing complexity through structure
Solution Approach 2:
Rather than designing the sprocket with uniform teeth and adding modifications, the invention inverts the approach by starting with the functional requirements of shifting operations and working backward to define the tooth configuration. The shifting initiation teeth and chain-supporting teeth are positioned based on the逆向 design logic of where they are needed most in the shifting cycle, simplifying the design process by following functional necessity rather than mechanical convention
Data Source
AI summary
A bicycle rear sprocket assembly is basically provided that includes a first sprocket including a first sprocket body and a plurality of first sprocket teeth provided to an outer periphery thereof. Each of a plurality of first circumferential areas has a first circumferential length. A first total number of the plurality of first circumferential areas is an even number. A first circumferential area counting number from a driving surface of a first shifting initiation tooth to a driving surface of a second shifting initiation tooth in a driving rotational direction of the bicycle rear sprocket assembly is an odd number. A second circumferential area counting number from the driving surface of the second shifting initiation tooth to the driving surface of the first shifting initiation tooth in the driving rotational direction is an odd number. The first circumferential area counting number is different from the second circumferential area counting number.