Offset Wide-Tooth Bicycle Chainring for Chain Retention
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Solution Overview
Problem
Traditional chainrings with uniformly aligned teeth struggle to maintain chain alignment, especially in rough terrain, leading to chain throwing and misalignment issues when front and rear sprockets are not co-planar.
Innovation Solution
A bicycle chainring design featuring a combination of teeth with varying widths and offsets, where some teeth are fully wide to fit within the wider spaces between outer chain links and others are partially offset to fit within narrower spaces, ensuring secure chain retention and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional chainrings use uniformly aligned teeth, then manufacturing is simple, but chain retention fails in rough terrain when front and rear sprockets are not co-planar
Solution Approach 1:
The chainring teeth are segmented into three distinct groups based on their width and offset characteristics: first group teeth with standard width centered on the chainring plane, second group teeth with reduced width offset inward, and third group teeth with reduced width offset outward. This segmentation allows each tooth type to serve specific functions in different chain positions, improving overall chain retention while maintaining manufacturability through systematic categorization.
Solution Approach 2:
Different regions of the chainring have teeth with locally optimized properties. Teeth in the first group are centered for standard chain engagement, while teeth in the second group are offset inward to accommodate chains when the front sprocket is higher than the rear, and teeth in the third group are offset outward for opposite conditions. This local quality optimization ensures reliable chain retention across varying terrain conditions without requiring a completely complex redesign.
2Reliability
If teeth are made with varying widths and offsets, then chain alignment is maintained in rough terrain, but manufacturing precision requirements increase
Solution Approach 1:
The tooth population is segmented into three clearly defined groups with distinct width and offset specifications. This segmentation allows manufacturers to produce each group type with standardized tolerances rather than requiring complex variable geometry across all teeth. The systematic categorization simplifies the manufacturing precision requirements compared to a continuously varying tooth design.
Solution Approach 2:
The invention employs discrete parameter changes rather than continuous variations. Each tooth group has specific width and offset parameters that are clearly defined and maintained within standard manufacturing tolerances. This approach to parameter changes is more manufacturable than designs requiring gradual or continuous parameter variations, as it allows for standardized tooling and quality control processes.
3Ease of manufacture
If all teeth are the same width, then manufacturing is easier, but chain tracking fails when sprockets are not co-planar
Solution Approach 1:
The chainring employs local quality variations where teeth in different groups have different widths and offsets optimized for specific chain tracking conditions. First group teeth are centered for standard operation, while second and third group teeth are offset inward and outward respectively to maintain chain tracking when front and rear sprockets are not co-planar. This localized optimization maintains ease of manufacture through systematic tooth types while solving the chain tracking reliability problem.
Solution Approach 2:
The uniform tooth design is segmented into three distinct tooth types with varying widths and offsets. This segmentation allows the chainring to adapt to different chain tracking conditions without requiring a completely non-uniform design. Each segment (tooth group) maintains simple geometric characteristics that are easy to manufacture, while the combination of segments provides the necessary adaptability for reliable chain tracking.
Data Source
AI summary
A bicycle chain ring having a plurality of teeth extending radially about an axis of the chain ring, the plurality of teeth including a first group of teeth and a second group of teeth. The first group of teeth has a first width at a tooth base that is sized to be received within a chain cavity defined between parallel links of a bicycle chain. The second group of teeth has a second width at the tooth base, the second width being different from the first width. Further, the first group of teeth have a tooth tip that is substantially centered on a plane defined between an inner surface and an outer surface of the chain ring and the second group of teeth is at least partially offset from the plane.