Bicycle Rear Suspension Leverage Curve Tuning
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Solution Overview
Problem
Current rear suspension designs for two-wheeled vehicles face challenges in tuning leverage curve characteristics without altering other kinematic traits, such as anti-rise and axle path, which affects the ride feel and sensitivity of the suspension.
Innovation Solution
The design incorporates an upper connecting member, a rear axle floating member, a lower connecting member, an upper shock actuation member, a pushrod member, and a damper member with specific pivotable couplings that allow the instant centre of rotation to move forward, enabling independent adjustment of leverage curve characteristics while maintaining desired anti-rise traits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the upper connecting link has a significantly longer distance between pivotable couplings than the lower connecting link (conventional four-bar linkage), then the instant centre moves forward as suspension is compressed, but it becomes difficult to tune leverage curve characteristics without materially altering other kinematic traits such as anti-rise and axle path
Solution Approach 1:
The patent divides the suspension system into two functionally independent subsystems: a four-bar linkage mechanism that controls anti-rise and axle path characteristics, and a separate shock actuation mechanism (comprising the upper shock actuation member, pushrod member, and damper member) that controls leverage curve characteristics. This segmentation allows independent tuning of leverage curve without affecting other kinematic traits, resolving the technical contradiction between adaptability and device complexity.
2Measurement precision
If a higher leverage ratio is used at the start of suspension travel, then sensitivity to trail or road surface inputs is improved, but the suspension may bottom out during high energy compression events
Solution Approach 1:
The patent implements a dynamic leverage ratio that changes progressively through suspension travel. The leverage ratio starts higher at the beginning of suspension travel to maximize sensitivity to road inputs, then decreases as suspension compression increases. This dynamic adjustment is achieved through the geometric configuration of the shock actuation mechanism, which automatically modifies the leverage ratio based on suspension position, thereby resolving the contradiction between sensitivity and resistance to bottoming out.
Solution Approach 2:
The patent changes the leverage ratio parameter throughout suspension travel to optimize performance. By designing the shock actuation mechanism with specific pivot points and link lengths, the system automatically adjusts the leverage ratio from higher values at extended positions to lower values at compressed positions, enabling the suspension to be both sensitive to small inputs and resistant to bottoming out during high-energy events.
Data Source
AI summary
A bicycle rear suspension based on a four bar configuration comprises an upper connecting member, a rear axle floating member, a lower connecting member, an upper shock actuation member, a pushrod member, and a damper member. A pivotable coupling couples a first location on the upper shock actuation member to a location on the front triangle, another pivotable coupling couples a second location on the upper shock actuation member to a first location on the pushrod member, and another pivotable coupling couples a second location on the pushrod member to a location on the lower connecting link member. The upper shock actuation member is pivotably coupled to the damper member. The upper shock actuation member and the pushrod member and the geometries of their respective pivotable couplings allow the leverage curve for the suspension to be defined independently of their kinematic traits, thereby providing improved rider feel and/or performance.