Bicycle Sprocket Guide Portions and Recesses for Chain Shifting
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Solution Overview
Problem
Current bicycle sprockets face challenges in smooth shifting operations and interference reduction between the sprocket and the bicycle chain, particularly during transitions between different sprockets, leading to inefficiencies and wear.
Innovation Solution
The design incorporates guide portions and recesses on the sprocket surface to facilitate smooth chain shifting, reduce interference, and enhance the chain-holding performance by strategically positioning these features to guide the chain and minimize contact points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If guide portions are added to the sprocket surface to guide the chain, then shifting smoothness is improved, but device complexity increases
Solution Approach 1:
The sprocket surface is segmented into multiple functional zones: guide portions for chain direction control, recesses for interference reduction, and tooth portions for power transmission. This segmentation allows each zone to perform its specific function optimally, resolving the contradiction by organizing complexity into manageable, purpose-driven segments.
Solution Approach 2:
Different regions of the sprocket are given different local qualities: the guide portions have smooth surfaces for chain guidance, the recesses create clearance zones, and the teeth provide engagement surfaces. This local differentiation improves shifting smoothness without requiring the entire sprocket to be redesigned, thus managing complexity effectively.
2Object-affected harmful factors
If recesses are provided on the sprocket surface to reduce interference, then chain-sprocket interference is reduced, but manufacturing complexity increases
Solution Approach 1:
Material is extracted from the sprocket body to form recesses in specific locations. These recesses remove potential interference points between the chain and sprocket body, directly addressing the harmful interference factor while maintaining a relatively simple manufacturing approach through material removal rather than addition.
Solution Approach 2:
The recesses are pre-formed during sprocket manufacturing to anticipate and prevent chain interference before it occurs during operation. This preliminary structuring of clearance zones ensures smooth chain movement without requiring complex real-time adjustments or post-manufacturing modifications.
3Reliability
If multiple guide portions and recesses are strategically positioned, then chain-holding performance is enhanced, but device complexity increases
Solution Approach 1:
The guide portions and recesses are arranged in specific circumferential and radial patterns around the sprocket. This dimensional organization creates a systematic approach to chain guidance and interference reduction, where the repetitive angular distribution of features provides reliable chain holding without requiring unique complex designs for each feature.
Data Source
AI summary
A bicycle sprocket comprises a first sprocket body, first sprocket teeth, a first side surface, a second side surface, at least one shifting facilitation projection, at least one guide portion, and at least one recess. The at least one guide portion is provided on a first side surface to guide a bicycle chain from the bicycle sprocket toward a smaller sprocket in a second shifting operation. The at least one recess is provided on the first side surface so as to be adjacent to the at least one guide portion in a circumferential direction defined about a rotational center axis. At least one of the at least one recess is provided in an upstream angular area defined from the at least one shifting facilitation projection to an upstream side in a driving state and within 90 degrees in the circumferential direction.