Rear Suspension Drivetrain Free Stroke for Pedal Kickback
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Solution Overview
Problem
Mountain bikes with rear suspension experience destabilizing pedal kickback and chain stress due to wheel travel, which current technologies fail to adequately address, especially in 'downhill' categories with higher travel limits.
Innovation Solution
A free stroke device is integrated into the drivetrain system, allowing controlled angular strokes with dual damping mechanisms to counteract pedal kickback, comprising elastic and hydraulic elements that provide progressive resistance during specific phases of the stroke, enhancing stability and pedaling comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If rear suspension travel is increased to improve ride comfort and handling, then the ability to absorb bumps and jumps is improved, but pedal kickback and chain stress increase causing instability and potential failure
Solution Approach 1:
A free-stroke device is introduced as an intermediary component between the chain and the crankset. This device includes a body with a free-stroke axis that allows the chain to move relative to the crankset without transmitting the full force of pedal kickback to the pedals. The intermediary absorbs and isolates the harmful shocks while maintaining drivetrain functionality.
Solution Approach 2:
The free-stroke device changes the operational parameters of the drivetrain by introducing controlled angular movement (free stroke) between the chain and crankset. This parameter change allows the system to accommodate suspension travel dynamics while preventing excessive force transmission to the pedals, thereby reducing pedal kickback.
2Stability of the object's composition
If rear suspension travel is increased to improve ride comfort and handling, then the ability to absorb bumps and jumps is improved, but chain stress increases causing potential chain breakage
Solution Approach 1:
The free-stroke device serves as a protective intermediary that isolates the chain from extreme stress conditions. By allowing controlled movement and absorbing shocks, it prevents the transmission of excessive forces that would otherwise lead to chain failure, thereby protecting the chain while maintaining the benefits of increased suspension travel.
Solution Approach 2:
The free-stroke device provides beforehand cushioning by being pre-configured to absorb and dissipate冲击 forces before they can propagate through the drivetrain to the chain. This prior cushioning mechanism prevents chain stress from reaching critical levels during impacts.
3Object-affected harmful factors
If a free stroke device with angular stroke is introduced to reduce pedal kickback, then stability is improved, but device complexity increases
Solution Approach 1:
The free-stroke device is segmented into distinct functional components: a body with a free-stroke axis, a crankset mounting interface, and a chain interface. This segmentation allows each component to perform its specific function independently while simplifying the overall design and making the device easier to manufacture and maintain.
Solution Approach 2:
The free-stroke device is designed with universal features that allow it to be integrated with standard crankset and chain interfaces. By incorporating multi-functionality to work with existing drivetrain components, the device reduces overall system complexity rather than increasing it, as it bridges the gap between suspension travel and standard drivetrain interfaces.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces pedal kickback, maintains pedaling efficiency, and increases the stability of the bicycle during suspension stresses, allowing for greater rear travel without chain breakage, thus improving the overall riding experience.
Implementation Method 1
said free stroke device comprises first damper means that act for the entire forward angular stroke (A1), opposing it
Implementation Method 2
said free stroke device comprises additional damper means that act only in a final stretch of forward angular stroke (A2), opposing it
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to a bicycle comprising a frame (5), a rear wheel (10), a suspension system (12) of the rear wheel with respect to the frame which allows a predetermined relative displacement (H1) between them, a drivetrain system of the motion (15) from a crankset (20) to the rear wheel (10), where the transmission system (15) includes a crankset (20) fixed to the frame (5), a hub and sprocket assembly (22) fixed to the wheel rear (10) rotatable around their common axis of rotation, and a transmission chain (24) placed to connect them directly to each other, where the crankset (20) and the hub and sprocket assembly (22) are subject to reciprocal displacement (H1) by the action of the suspension system, where at least one of the crankset (20) and the hub and sprocket assembly (22) includes a free travel device (40, 140) placed to allow both a forward and backward free angular stroke (Al) of the chain (24) with respect to the respective rotation axes (X, x1) of the crankset and / or of the hub and pinion assembly, where the angular stroke is limited to a predetermined angle (A1) of an amount related to said relative displacement (H1) between the wheel (10) and frame (5).