Bicycle Hub Axial Spline Force Transmission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current bicycle hub assemblies face challenges in efficiently transmitting pedaling force and allowing freewheeling due to limitations in spline tooth design and axial length, which affect the overall performance and efficiency of the bicycle drivetrain.
Innovation Solution
A bicycle hub assembly design featuring a hub axle, hub body, and sprocket support body with specific axial lengths and external spline teeth configurations that engage with a bicycle rear sprocket assembly, allowing for effective pedaling force transmission and freewheeling by incorporating a freewheel structure that separates ratchet members during coasting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the axial length of the hub body is increased to improve pedaling force transmission, then the engagement between spline teeth is enhanced, but the overall device complexity increases
Solution Approach 1:
The patent transitions from radial force transmission to axial force transmission by extending the hub body in the axial direction. The spline teeth are arranged axially along the hub body length, allowing pedaling force to be transmitted through axial engagement rather than radial engagement, thereby improving force transmission without increasing radial dimensions
Solution Approach 2:
The hub body is divided into multiple functional segments including a first spoke-mounting portion, a second spoke-mounting portion, and a sprocket support body. Each segment has specific functions: the spoke-mounting portions accommodate spokes at different axial positions, while the sprocket support body provides spline tooth engagement for power transmission, allowing optimized force distribution
2Strength
If the radial length of external-spline driving surfaces is increased to improve force reception, then the engagement surface area increases, but the device complexity increases
Solution Approach 1:
The external spline teeth are designed with differentiated local properties: the driving surfaces have increased radial length (7mm or more) to maximize force reception area, while non-driving surfaces have reduced radial length. This localized optimization ensures that force transmission occurs at the most effective positions without uniformly increasing the complexity of the entire spline structure
Solution Approach 2:
The patent extends the driving surfaces in the radial direction rather than increasing axial length or circumferential width. By increasing the radial length of the driving surfaces, the engagement area is maximized in the most efficient dimension for force transmission, improving strength without proportionally increasing overall device complexity
3Adaptability or versatility
If the hub body axial length is increased to accommodate multiple spoke-mounting portions, then spoke distribution is improved, but the device complexity increases
Solution Approach 1:
The hub body is segmented into distinct functional zones: first spoke-mounting portion, second spoke-mounting portion, and sprocket support body. This segmentation allows spokes to be mounted at different axial positions with optimized spacing, improving adaptability for different wheel configurations while maintaining a modular structure that manages complexity
Solution Approach 2:
The extended hub body structure serves multiple functions simultaneously: it provides axial spacing for multiple spoke-mounting portions, accommodates the sprocket support body with spline teeth, and maintains structural integrity for force transmission. This multi-functionality increases adaptability without proportionally increasing complexity
Data Source
AI summary
A bicycle hub assembly comprises a hub axle, a hub body, and a sprocket support body. The hub body includes a first spoke-mounting portion, a second spoke-mounting portion, and a first axial length. The first axial length is defined between a first axially outermost part of the first spoke-mounting portion and a second axially outermost part of the second spoke-mounting portion in an axial direction and is equal to or larger than 55 mm. The sprocket support body includes a plurality of external spline teeth. The plurality of external spline teeth includes a plurality of external-spline driving surfaces. The plurality of external-spline driving surfaces each includes a radial length defined from a radially outermost edge to a radially innermost edge. A total of the radial lengths of the plurality of external-spline driving surfaces is equal to or larger than 7 mm.