Bicycle Rear Sprocket Splines for Lower Tooth Load and Weight
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Solution Overview
Problem
Bicycle rear sprocket assemblies with fewer internal spline teeth face challenges in durability and material selection, as they experience higher rotational forces, limiting the choice of materials without compromising durability.
Innovation Solution
Incorporating at least ten internal spline teeth with varying pitch angles and sizes, and an internal cavity with a larger outer diameter than the spline major diameter, reduces rotational forces and allows for more material options while improving mounting precision and weight reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the number of internal spline teeth is reduced to fewer than ten, then the device complexity and weight are reduced, but the rotational force per tooth increases reducing durability
Solution Approach 1:
The patent changes the parameter of the number of internal spline teeth from conventional fewer than ten to at least ten, which fundamentally alters the force distribution characteristics. This parameter change reduces the rotational force per tooth while maintaining compact design, resolving the contradiction between device simplicity and durability.
2Ease of manufacture
If the number of internal spline teeth is reduced, then the manufacturing cost and complexity are reduced, but the material selection freedom is limited due to durability requirements
Solution Approach 1:
By changing the parameter of internal spline teeth count to at least ten, the patent reduces operational stress on each tooth. This enables the use of lighter, less durable materials that would otherwise be unsuitable, thereby expanding material selection freedom while maintaining manufacturing simplicity.
3Weight of moving object
If the internal cavity diameter is increased beyond the spline major diameter, then the weight is reduced, but the structural strength is compromised
Solution Approach 1:
The patent segments the sprocket structure by creating an internal cavity that separates the functional spline teeth region from the central hub area. This segmentation allows the cavity diameter to exceed the spline major diameter while maintaining structural integrity through the distributed spline teeth configuration, achieving weight reduction without compromising strength.
Data Source
AI summary
A bicycle rear sprocket assembly comprises at least one sprocket and an internal cavity. The at least one sprocket includes at least ten internal spline teeth configured to engage with a bicycle hub assembly. The at least ten internal spline teeth have an internal-spline major diameter. The internal cavity has a maximum outer diameter larger than the internal-spline major diameter.