Bicycle Stem Fixing Arrangement With Flared Seats
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Solution Overview
Problem
Existing fixing arrangements between the steering system and the fork of bicycles, particularly in road racing bikes, compromise ease of mounting/unmounting and structural integrity due to the need for through holes and screws, which are not suitable for applications with suspension/shock absorber systems inside the steering head tube.
Innovation Solution
A fixing arrangement featuring a disc-shaped flange on the stem with flared seats for screws and a centering shaft for precise alignment, allowing for easy assembly and maintenance without through holes in the fork, ensuring structural strength and compatibility with suspension systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If through holes and screws are used to fix the stem to the fork, then the connection strength is improved, but the ease of mounting and unmounting deteriorates
Solution Approach 1:
The fixing arrangement is divided into separate functional elements: a flange with flared seats on the stem, and corresponding recesses in the fork. This segmentation allows the stem to be fixed without requiring through holes in the fork, enabling easy mounting and unmounting while maintaining connection strength through the flared seats that distribute load across multiple contact points.
2Reliability
If through holes are made in the fork for fixing screws, then the connection reliability is improved, but the structural integrity of the fork deteriorates
Solution Approach 1:
The harmful element (through holes) is extracted from the fork structure. Instead of drilling through the fork, the invention uses a flange with flared seats that press against the fork surface through recesses. This eliminates the need for through holes, preserving the fork's structural integrity while maintaining connection reliability through the distributed contact of the flared seats.
3Weight of moving object
If a compact fixing arrangement is used inside the steering head tube, then the weight and bulk are reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The flared seats are designed with specific geometric characteristics that concentrate the fixing function in a localized area on the flange. This local quality allows the compact arrangement to achieve reliable fixation without requiring high precision throughout the entire steering system, as the flared seats naturally distribute and accommodate minor dimensional variations.
Data Source
Figure 1~1a
Figure 2~3
Figure 4a~4b
AI summary
The present invention is in connection with the field of the cycling industry, and in particular it refers to a steering system for a bicycle, more specifically to a fixing arrangement between the steering system and the fork of the bicycle. The fixing arrangement according to the invention is advantageously, but not necessarily, adapted for association with a suspension of the single-stem type adapted to be arranged inside the steering head tube and specially conceived, thanks to its compactness, to equip road "racing" bikes.