Bicycle Rear Suspension Decoupling Axle Path and Rate
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Solution Overview
Problem
Existing rear wheel suspension systems for bicycles often react to drivetrain and braking forces, leading to unwanted energy loss and compromised ride quality, as they fail to decouple suspension rate from rear wheel trajectory effectively.
Innovation Solution
A six-bar type suspension system with specific linkages and a shock absorber configuration that decouples rear wheel axle movement from suspension rate, allowing independent adjustment of suspension rate and rear wheel trajectory, thereby minimizing energy loss and improving ride quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a traditional rear wheel suspension system is used, then the suspension can absorb ground forces, but it also reacts to drivetrain and braking forces causing unwanted energy loss
Solution Approach 1:
The suspension system is segmented into multiple independent linkages (first link, second link, third link, fourth link) that work together to isolate the shock absorber from drivetrain and braking forces. This segmentation allows the suspension to respond only to ground forces while preventing energy loss from unwanted movements.
Solution Approach 2:
The multi-linkage system acts as an intermediary mechanism between the shock absorber and the drivetrain components. By introducing these intermediate linkages, the system prevents direct transmission of drivetrain and braking forces to the suspension, thereby eliminating unwanted energy loss while maintaining ride quality.
2Adaptability or versatility
If the suspension rate and rear wheel trajectory are coupled, then the structure is simpler, but independent adjustment of suspension parameters is not possible
Solution Approach 1:
The suspension system is divided into separate functional modules: the shock absorber handles suspension rate adjustment while the multi-linkage system (first link, second link, third link, fourth link) independently controls rear wheel trajectory. This segmentation enables independent adjustment of both parameters without increasing overall system complexity.
Solution Approach 2:
The suspension system incorporates dynamic characteristics through its multi-linkage design, allowing the rear wheel trajectory to be independently controlled from the suspension rate. The geometric relationships between the links enable precise control over wheel path while the shock absorber independently manages suspension compression characteristics.
3Stability of the object's composition
If a six-bar type suspension system is used, then the degrees of freedom are limited to one, but the system becomes more complex
Solution Approach 1:
The suspension system is segmented into six distinct linkages (first link, second link, third link, fourth link, and their connections) that work together to limit the system to one degree of freedom. This segmentation provides stability by ensuring the rear wheel follows a controlled path while absorbing ground forces, despite the increased number of components.
Data Source
AI summary
A bicycle rear wheel suspension system includes a first link and a second link both pivotally attached to the main frame and to a rear stay or swingarm member. A third link is activated by the first or the second link. The third link activates a fourth link. Either the third or the fourth link can be attached to the main frame at one pivot point. One end of the shock absorber is attached to the third or fourth link at another pivot point. The shock absorber has its other end attached to the first or second link that is not receiving said third link. The third and fourth links are responsible for tuning of the suspension rate characteristics, whereas the first and second links are responsible for precisely defining the rear wheel axle trajectory as the suspension system compresses.