Bicycle Front Derailleur Projection Chain Drop Prevention
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Solution Overview
Problem
Bicycle front derailleurs often fail to prevent the chain from falling off the smallest front chain ring, especially on uneven terrain or dual suspension bicycles, leading to unreliable shifting and potential mechanical issues.
Innovation Solution
A bicycle front derailleur assembly with a projection part attached to the seat tube, featuring a projecting surface that prevents the chain from falling off the smallest front chain ring, designed to be compatible with various frame types, including dual suspension frames, and ensuring smooth shifting even in extreme conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a guide portion is formed on a thin bottom bracket mounting plate, then chain dropping is reduced, but the structure lacks rigidity and does not perform optimally on dual suspension bicycles
Solution Approach 1:
The mounting structure is divided into two separate components: a rigid mounting plate that attaches to the frame and a separate guide portion that attaches to the mounting plate. This segmentation allows each component to be optimized independently - the mounting plate for rigidity and the guide portion for chain retention.
Solution Approach 2:
The guide portion is nested onto the mounting plate, forming a layered structure where the thinner guide portion attaches to the rigid mounting plate. This nested arrangement combines the rigidity of the mounting plate with the chain-guiding functionality of the guide portion, solving both the strength and reliability issues.
2Stability of the object's composition
If the front derailleur is rigidly attached to the seat tube, then shifting stability is improved, but compatibility with various frame types including dual suspension frames is reduced
Solution Approach 1:
The mounting plate is designed with universal mounting features that can accommodate different frame types including dual suspension frames. The separate mounting plate acts as an adapter that provides consistent mounting geometry across various frame configurations, enabling the derailleur to maintain stable shifting performance while being compatible with diverse frame designs.
Data Source
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AI summary
A bicycle front derailleur (12) includes a fixed member (22), a chain guide (28) and a linkage assembly (30). The fixed member (22) includes a fixing body (34) and a projection part (36) fixedly coupled together. The fixing body (34) includes a fastening portion (44) with a seat tube reference plane that aligns with a longitudinal center axis of a seat tube when coupled thereto. The projection part (36) has a projecting surface offset axially from the fixing body (34) toward a smallest front chain ring of a bicycle front crankset. The projecting surface has an overall vertical height lying substantially in a single plane measured in a direction parallel to the seat tube reference plane that is greater than 10 millimeters in an area between the seat tube reference plane and 23 millimeters measured perpendicularly and forwardly from the seat tube reference plane.