Bicycle Fork Crown Segmentation for Weight Reduction
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Solution Overview
Problem
Bicycle fork designs face a trade-off between reducing weight to enhance maneuverability and maintaining mechanical strength to prevent breakage and accidents, particularly during downhill motion.
Innovation Solution
A bicycle fork crown with a through housing featuring a recess and non-contiguous inner annular bearing surfaces, along with a fork pivot with varying outer annular bearing surfaces and a frustoconical portion, reduces weight while preserving mechanical stress resistance through optimized material distribution and stress management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the weight of the fork crown is reduced to improve maneuverability, then the weight decreases and maneuverability improves, but the resistance to mechanical stresses decreases leading to potential breakage
Solution Approach 1:
The fork crown is segmented by introducing a radial groove that divides the bearing surfaces into two separate annular zones. This segmentation allows material removal in the groove area to reduce weight while maintaining structural integrity through the distributed bearing zones. The groove effectively partitions the load-bearing function across two distinct annular surfaces rather than a continuous surface, enabling weight reduction without compromising overall strength.
Solution Approach 2:
The radial groove creates local quality variations in the fork crown structure. The groove area has reduced material content for weight reduction, while the two annular bearing surfaces maintain high material density and structural strength where needed. This local differentiation allows the structure to be lightweight in non-critical areas while remaining strong in load-bearing zones, resolving the contradiction between weight reduction and strength maintenance.
2Weight of moving object
If material is removed from the fork crown to reduce weight, then weight decreases and maneuverability improves, but the structural integrity and resistance to breakage deteriorates
Solution Approach 1:
The radial groove segments the bearing surface into two annular zones that are distributed along the pivot length. This segmentation strategy removes material from the groove region to reduce weight while preserving reliability through the distributed bearing zones that collectively support the pivot. The two separated annular surfaces provide adequate load distribution to prevent breakage despite material removal.
Solution Approach 2:
The radial groove introduces a dimensional feature that extends axially along the pivot length, creating two distinct annular bearing zones separated in the axial dimension. This dimensional approach allows weight reduction through material removal in the radial groove while maintaining reliability through the extended bearing surfaces distributed along the length of the pivot, effectively using the third dimension to resolve the weight-strength trade-off.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The bicycle fork head includes a through housing (11) intended to fixedly receive a bicycle fork pivot (20), said housing (11) having a chamber defining a groove interposed between two internal annular bearing surfaces (13, 14) for said pivot (20).