Eccentric Bicycle Fork Shaft Internal Cable Routing
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Solution Overview
Problem
Existing bicycle fork designs compromise mechanical stability and adjustability when attempting to integrate brake and gear shift cables internally, often requiring special components and leading to reduced stiffness and imprecise shifting/braking due to flattened fork shafts or complex cable routing.
Innovation Solution
A bicycle fork with a cylindrical fork shaft segment configured eccentrically to the steering axis, allowing for internal cable guidance without compromising mechanical stability, using standard components and maintaining adjustability through a reduction sleeve and cap ring for secure cable routing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the fork shaft is flattened to create internal cable guidance space, then cable routing is improved, but mechanical stability and bending stiffness deteriorate
Solution Approach 1:
The patent places cable guides and cable routing structures inside the hollow interior space of the cylindrical fork shaft segment. The cables are routed through the interior cavity of the fork shaft, nesting the cable management system within the existing structural component without altering the external cylindrical shape, thereby maintaining bending stiffness while enabling internal cable guidance.
Solution Approach 2:
The patent utilizes the hollow interior dimension of the fork shaft to route cables, transitioning from external or surface-level cable routing to internal three-dimensional space utilization. This allows cables to pass through the interior volume of the fork shaft, providing clean cable management without compromising the external structural integrity.
2Ease of operation
If special expander components are used for internal cable guidance, then cable routing capability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent employs standard expander components that are commonly used in bicycle headset assemblies for their primary function of securing the fork shaft. These same expander components are utilized to provide cable guidance functionality, making the expander serve multiple purposes: structural support and cable routing. This eliminates the need for specialized cable guidance components.
Solution Approach 2:
The reduction sleeve, primarily designed to reduce the diameter of the fork shaft for bearing engagement, is also configured with features that facilitate cable guidance and routing. This multi-functional design allows a single component to address both structural requirements and cable management needs.
3Adaptability or versatility
If the fork shaft projects above the handlebar stem to allow height adjustment, then adjustability is improved, but the ability to compress and brace the stem deteriorates
Solution Approach 1:
The patent allows the fork shaft to project above the handlebar stem during the assembly and compression process, enabling the stem and spacers to be properly positioned and compressed against the head tube. Once assembled, the fork shaft maintains its projected position, allowing for future height adjustments of the handlebar stem while the compression structure remains intact and functional.
Solution Approach 2:
The fork shaft is designed to project above the handlebar stem during assembly to facilitate the preliminary action of compressing and bracing the stem against the head tube. This projected position allows workers to properly seat the stem and spacers before final tightening, ensuring correct alignment and compression while maintaining the ability to adjust stem height later.
4Ease of manufacture
If a cover is provided to facilitate compression of the stem and spacers, then assembly ease is improved, but device complexity increases
Solution Approach 1:
The patent utilizes the reduction sleeve, which is already required for reducing the fork shaft diameter to fit the headset bearings, as a multi-functional component that also facilitates the compression and bracing of the handlebar stem and spacers. The reduction sleeve's structure and positioning enable workers to compress the stem assembly against the head tube without requiring an additional separate cover component.
Data Source
AI summary
A bicycle fork includes a fork shaft configured to be rotatably borne by headset bearings in a head tube of a bicycle frame so as to rotate about a steering axis. The fork shaft includes a cylindrical fork shaft segment that is disposed eccentrically with respect to the steering axis. The cylindrical fork shaft segment is a right circular cylinder having a hollow interior, a cylindrical inner surface and a central longitudinal axis that lies within a symmetry plane of the bicycle frame and extends parallel to the steering axis. The central longitudinal axis of the cylindrical fork shaft segment is spaced apart from the steering axis in a direction of eccentricity that points in an opposite direction with respect to a forward direction of travel of the bicycle.