Front Derailleur Base Member Positioning for Large Wheel Clearance
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Solution Overview
Problem
Conventional front derailleurs face challenges in maintaining sufficient space between the base member and the rear wheel when a bicycle uses a rear wheel of larger diameter, leading to potential interference and reduced performance.
Innovation Solution
The front derailleur design includes a base member with an attaching bore positioned forward and above the chain guide, allowing for a more forward and upward fixation on the bicycle frame, along with a link mechanism that includes pivotally arranged link axes to create a four-bar link mechanism, ensuring stable chain guide movement and compact configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rear wheel of a larger diameter is used to improve traveling performance, then the traveling performance is improved, but the space between the base member and the rear wheel is decreased
Solution Approach 1:
The attaching bore is positioned not only forward but also above the chain guide, utilizing vertical space to achieve the required distance. This two-dimensional positioning (forward and upward) allows the base member to be located in a space that would otherwise be unavailable, resolving the contradiction between large wheel diameter and sufficient clearance.
2Length of moving object
If the base member is positioned forward to increase space with the rear wheel, then the space is increased, but the chain guide positioning becomes more constrained
Solution Approach 1:
By positioning the attaching bore above the chain guide in addition to forward, the invention creates sufficient space without requiring extreme forward positioning that would constrain chain guide operation. The vertical dimension provides the necessary clearance while maintaining horizontal positioning flexibility for proper chain guide function.
3Length of moving object
If the attaching bore is entirely disposed in front of and above the chain guide to maximize forward positioning, then the space with the rear wheel is maximized, but the base member configuration becomes more complex
Solution Approach 1:
The base member is designed with the attaching bore positioned above and forward of the chain guide, allowing it to simultaneously achieve maximum forward positioning for clearance while maintaining proper chain guide alignment and function. This multi-functional positioning resolves the contradiction by making the base member configuration serve multiple purposes: maximizing space while enabling proper operation.
Data Source
AI summary
A front derailleur is attachable to a bicycle with a frame in which a fixing bore is provided. The front derailleur basically includes a base member, a chain guide and a link mechanism. The base member has an attaching bore for attaching the base member to a fixing bore of a frame by a fastening member. The chain guide configured to guide a chain. The link mechanism movably couples the chain guide to the base member. The base member is disposed with respect to the chain guide such that at least a part of the attaching bore is disposed in front of the chain guide and above the chain guide while the front derailleur is in a state in which the base member is attached to the frame.