Coaxial Rear Derailleur Locking for Precise B-Gap Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rear derailleurs face issues with unintentional shifting due to oblique pivot mechanisms, enlarged dimensions for high gear spreads, complex and inaccurate B-gap adjustments, and the need for multiple people to adjust the B-gap in sag positions, especially in frames with rear wheel suspension.
Innovation Solution
A rear derailleur with a blocking device that allows for adjustable locking between the chain guide assembly and the P-knuckle, enabling simple, accurate B-gap adjustment and sag compensation, and a method to adjust the derailleur based on bicycle category, using a blocking device with multiple positions for different bicycle types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an oblique parallelogram pivot mechanism is used to approach sprockets of dissimilar sizes, then the gear spread capability is improved, but the susceptibility to unintentional shifting procedures increases
Solution Approach 1:
The blocking device applies a preliminary counteracting force to prevent the chain guide assembly from moving unintentionally. By positioning the blocking element to engage with the chain guide assembly before unintentional shifting can occur, the system counteracts the harmful effect of the oblique parallelogram mechanism's susceptibility to ghost shifting while maintaining the ability to approach sprockets of dissimilar sizes
2Adaptability or versatility
If the dimension of the derailleur is enlarged to operate increased number of sprockets, then the gear spread capability is improved, but the device complexity increases
Solution Approach 1:
The blocking device introduces a dynamic adjustment capability that allows the derailleur to adapt to different gear spreads without requiring a permanently enlarged structure. By enabling the chain guide assembly to be positioned and locked at optimal locations, the system can accommodate increased numbers of sprockets while avoiding the need for a consistently larger derailleur body, thus reducing overall device complexity
3Manufacturing precision
If the B-gap adjustment process is made complex to achieve precise positioning, then the manufacturing precision is improved, but the ease of operation deteriorates
Solution Approach 1:
The blocking device enables the chain guide assembly to self-lock at precisely determined positions relative to the movable element. The blocking element automatically engages with the chain guide assembly when the blocking device is in the second position, eliminating the need for complex manual adjustment procedures while maintaining high positioning precision. This self-servicing mechanism allows users to achieve accurate B-gap settings without requiring sophisticated adjustment tools or procedures
4Manufacturing precision
If multiple people are required to adjust the B-gap in sag position, then the manufacturing precision is improved, but the ease of operation deteriorates
Solution Approach 1:
The blocking device creates a self-servicing adjustment system that maintains high B-gap adjustment accuracy without requiring multiple people or special equipment. The blocking element automatically engages with the chain guide assembly at precisely determined positions, allowing a single user to achieve accurate adjustments independently, even in sag position, thereby eliminating the need for additional personnel or specialized adjustment tools
Data Source
AI summary
The disclosure relates to an electromechanical rear derailleur for coaxial assembling on a rear wheel axle. The derailleur has a base element, a pivot mechanism, and a movable element having a chain guide assembly. The chain guide assembly is connected to the movable element so as to be rotatable about a rotation axis. A blocking device permits the chain guide assembly to be established relative to the movable element. The blocking device is able to be inserted into the movable element in two different positions.