Offset-Tooth Chainring to Prevent Chain Stay Contact
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Solution Overview
Problem
Bicycles with chain-driven drivetrains face challenges in managing chain engagement and tension, especially over rough terrain, leading to potential frame and chainring damage due to chain interaction with the chain stay under high load conditions.
Innovation Solution
A bicycle chainring design featuring alternating wider and narrower teeth, with offset top lands, to effectively engage and guide the chain, reducing chain tension and preventing frame deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional chainring design is used, then the structure is simple, but chain engagement is unreliable under high load and rough terrain conditions
Solution Approach 1:
The chainring teeth are segmented into two distinct groups: a first group of narrower teeth and a second group of wider teeth. This segmentation allows each tooth type to serve different functions - the narrower teeth provide standard engagement while the wider teeth provide enhanced chain guidance and engagement stability under high load conditions, thereby improving overall reliability without excessive complexity
Solution Approach 2:
Different regions of the chainring have different tooth characteristics. The first group of teeth has a narrower width suitable for normal operation, while the second group of teeth has a wider width for enhanced engagement. This local variation in tooth quality allows the chainring to adapt to different loading conditions and terrain challenges, improving reliability where needed while maintaining simplicity elsewhere
2Strength
If chain tension management is not optimized, then the drivetrain is simple, but frame deformation and damage occur under high load
Solution Approach 1:
The chainring teeth are designed with offset top lands that protrude toward the chain stay before the chain experiences excessive tension or contact with the chain stay. This preliminary geometric feature proactively manages chain tension by guiding the chain onto the teeth earlier in the rotation cycle, preventing the chain from contacting the chain stay and causing frame deformation or damage
Data Source
AI summary
A bicycle chainring for engagement with a drive chain includes a plurality of teeth extending from a periphery of the chainring wherein roots of the plurality of teeth are disposed adjacent the periphery of the chainring. The plurality of teeth include a first group of teeth and a second group of teeth.