Collapsible Bicycle Frame With Pivot-Locked Diamond Geometry
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Solution Overview
Problem
Conventional folding bicycles deviate from the 'diamond frame' configuration, compromising riding performance, comfort, and rigidity due to non-conventional frame geometry and added weight from hinges, while maintaining conventional frame geometry is desirable for improved handling and road performance.
Innovation Solution
A bicycle frame design featuring a rear frame structure with a seat tube, bottom bracket shell, and chainstays, connected to a front frame structure via a pivot at the bottom bracket, allowing for a crossbar to immobilize the pivot in the riding position and facilitate vertical pivoting for collapse, with arms providing clearance for wheel and drivetrain components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional folding bicycles use non-conventional frame geometry and hinges to enable folding, then the bicycle can be collapsed for transport and storage, but the rigidity and riding performance are compromised
Solution Approach 1:
The frame is divided into two separate structures (front frame structure and rear frame structure) that can pivot relative to each other. The front frame structure includes a down tube and head tube, while the rear frame structure includes a seat tube and chainstays. These segmented structures are connected through a pivot mechanism that allows folding while maintaining the integrity of each individual frame segment.
Solution Approach 2:
The frame incorporates a dynamic pivot connection between the front and rear frame structures that allows the frame to transition between rigid (riding condition) and flexible (collapsed condition) states. The pivot enables relative movement between frame structures when needed while maintaining structural integrity during normal operation.
2Adaptability or versatility
If hinges are added to enable frame pivoting, then the bicycle can be collapsed, but the weight of the bicycle increases
Solution Approach 1:
The frame uses a dynamic pivot connection that provides the necessary movement capability without requiring heavy-duty hinges. The pivot allows controlled relative movement between frame structures while maintaining adequate structural support, thereby minimizing the additional weight required for the folding mechanism.
3Volume of moving object
If the front frame structure pivots relative to the rear frame structure, then the bicycle can be collapsed to a compact form, but the complexity of the frame structure increases
Solution Approach 1:
The frame is segmented into distinct front and rear frame structures that can move independently relative to each other. This segmentation allows the frame to collapse into a compact configuration while keeping each individual segment relatively simple in design, avoiding the need for complex integrated mechanisms.
Solution Approach 2:
The frame employs a dynamic pivot connection that enables straightforward relative movement between the front and rear frame structures. This dynamic connection simplifies the overall mechanism compared to more complex folding systems by allowing natural pivoting motion that achieves compact folding without intricate linkages or multiple moving parts.
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
A bicycle and frame is disclosed including a rear frame structure including a seat tube, a bottom bracket shell and a chainstay terminating in a rear wheel mount. A forward end of the chainstay, a lower end of the seat tube, and the bottom bracket shell are rigidly connected. A front frame structure includes a down tube rigidly connected to a forwardly disposed head tube and connected to the rear frame at a pivot proximate the bottom bracket shell facilitating pivoting of the front frame with respect to the rear frame in a common vertical plane. A frame lock when engaged substantially immobilizes the pivot to place the frame in a riding condition and when disengaged facilitates relative movement of the down tube and the seat tube towards each other about the pivot in the common vertical plane to place the frame in a collapsed condition such that the down tube lies alongside the seat tube.