Bicycle Sprocket Support Splines for Lower Tooth Load
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Solution Overview
Problem
Existing bicycle hub assemblies with fewer than ten external spline teeth face challenges in durability and material selection, as they tend to have higher rotational forces applied to each tooth, limiting the choice of materials without compromising durability.
Innovation Solution
A sprocket support body with at least ten external spline teeth, configured to be rotatably mounted on a hub axle, is designed to engage with a bicycle rear sprocket assembly. These teeth have specific dimensions and angles to reduce rotational force, improve durability, and allow for a wider range of material choices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of external spline teeth is increased to at least ten, then the rotational force applied to each tooth is reduced, improving durability, but the device complexity increases
Solution Approach 1:
The load transmission function is segmented across multiple spline teeth (at least ten), distributing the rotational force from the bicycle rear sprocket assembly across numerous contact points. This segmentation reduces the force burden on each individual tooth, enhancing durability while maintaining a manageable structural complexity through standardized tooth geometry.
2Strength
If the radial length of external-spline driving surfaces is increased to at least 7 mm total, then the strength of the sprocket support body is improved, but the manufacturing complexity increases
Solution Approach 1:
The radial length parameter of the external-spline driving surfaces is optimized to a total of at least 7 mm, providing sufficient contact area and load-bearing capacity for enhanced strength. This parameter is configured to balance mechanical performance with manufacturability, allowing standard machining processes to achieve the required dimensions without excessive complexity.
3Force
If the first external-spline-surface angle is set between 0 to 10 degrees, then the force distribution across spline teeth is optimized, but the manufacturing precision requirements increase
Solution Approach 1:
The first external-spline-surface angle is configured within a relatively wide range of 0 to 10 degrees, which optimizes force distribution across the spline teeth during operation. This angular parameter is designed to accommodate typical manufacturing tolerances while maintaining effective load transmission, avoiding overly tight precision requirements that would complicate manufacturing.
Data Source
AI summary
A sprocket support body comprises at least ten external spline teeth including a plurality of external-spline driving surfaces. The plurality of external-spline driving surfaces each includes a radially outermost edge, a radially innermost edge, and a radial length. A total of the radial lengths of the plurality of external-spline driving surfaces is equal to or larger than 7 mm. At least one external-spline driving surface has a first external-spline-surface angle. The first external-spline-surface angle ranges from 0 degree to 10 degrees. One tooth of the at least ten external spline teeth having a first circumferential spline size. The other teeth of the at least ten external spline teeth each have a second circumferential spline size that is smaller than the first circumferential spline size. A total number of the other teeth of the at least ten external spline teeth being equal to or larger than nine.