Rotatable Bicycle Stem Reducing Folded Size
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Solution Overview
Problem
Conventional folding bicycles face challenges in achieving a smaller, more compact folded size due to a fixed length between the stem and handlebar rotating centers, leading to increased storage and shipping space requirements, especially for electric bicycles with complex handlebar mechanisms.
Innovation Solution
A rotatable folding bicycle stem with two rotating axes, where the stem rotating axis is closer to the O-shaped loop than the standpipe rotating axis, allowing for a 0 to 30-degree angle and a spring-loaded positioning pin mechanism for secure attachment, enabling the stem to be rotated 90 degrees and reducing the folded size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the handlebar is designed to disassemble or detach from the bike, then the folded size is reduced, but the device complexity and ease of operation deteriorate due to troublesome assembly and disassembly processes
Solution Approach 1:
The stem is nested within the standpipe, with the stem receiving groove positioned inside the standpipe receiving portion. This nested configuration allows the stem to be stored within the standpipe when not in use, reducing the overall folded size without requiring separate storage compartments or complex disassembly mechanisms.
Solution Approach 2:
The stem is divided into multiple segments that can rotate relative to each other around different rotating axes. The first rotating axis allows the stem to rotate relative to the standpipe, while the second rotating axis enables further rotation of the stem segments. This segmentation enables compact folding while maintaining simple operation through intuitive rotational movements.
2Volume of moving object
If the handlebar is rotated 90 degrees to be paralleled along the frame, then the folded size is reduced, but the manufacturing precision and adaptability are compromised
Solution Approach 1:
The stem is designed with dynamic rotational capabilities around two different axes, allowing it to adapt to various folding configurations. The first rotating axis enables rotation relative to the standpipe, while the second rotating axis provides additional rotational freedom. This dynamic design allows the stem to achieve compact folded positions while maintaining standardization and avoiding the need for customized production for different folding angles.
3Device complexity
If the length between the rotating center of the stem and the handlebar is fixed, then the structure is simple, but the folded size cannot be reduced further
Solution Approach 1:
Instead of reducing the folded size by shortening the stem length in one dimension, the invention introduces rotation around a second axis that is not collinear with the first rotating axis. This dimensional change allows the stem to achieve compact folded positions through rotational movement in multiple dimensions, maintaining the original stem length while significantly reducing the overall folded footprint.
4Volume of moving object
If the stem rotating axis is closer to the O-shaped loop than the standpipe rotating axis, then the folded size is reduced, but the positioning precision requirements increase
Solution Approach 1:
The positioning pin and positioning pin groove automatically engage to lock the stem in its rotated position, providing self-positioning and self-locking functionality. The spring-loaded positioning pin ensures reliable engagement with the groove, maintaining positioning accuracy while allowing for normal manufacturing tolerances. This self-service mechanism eliminates the need for complex external positioning systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution allows for a more compact folded bicycle design, reducing storage space and shipping costs, while facilitating easier assembly and disassembly, and increasing loading capacity in containers.
Implementation Method 1
A spring is mounted at a bottom of the positioning pin inserted inside the positioning pin groove of the standpipe receiving portion
Data Source
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AI summary
A rotatable folding bicycle stem comprises a stem (20) rotatably mounted on the standpipe with defining a stem rotating axis (B). An upper end of the stem (20) terminates in a forwardly projecting O-shaped loop (23). A distance between the stem rotating axis (B) to a center of the O-shaped loop (23) is smaller than a distance between the standpipe rotating axis (A) to the center of the O-shaped loop (23). Compared with the conventional folding bicycle, a space between a handlebar and a frame (D) could be reduced or became smaller by utilizing the present invention. The present invention is able to provide a smaller folded size of the folding bicycle for facilitating storage by users and benefiting for being stacked or compacted more tightly when loading in a cargo car of a container for delivery. The present invention could reduce a shipping cost for a single bike and increase a loading quantity in single container.