Bike Rear Suspension Leaf Spring for Pivot-Free Vertical Flex
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Solution Overview
Problem
Existing rear wheel suspension systems for bikes face challenges in achieving a balance of adjustability, low friction, low weight, low maintenance, and pleasing aesthetics, particularly in low-mid travel configurations (up to 80mm of rear wheel suspension, with issues such as complexity, weight, and maintenance due to pivots, sliding surfaces, and supplemental suspension units.
Innovation Solution
A rear wheel suspension system utilizing a leaf spring interconnecting seatstays and a seat tube, with adjustable stiffness inserts that allow vertical flex without pivots or sliding surfaces, enabling lightweight, low-maintenance, and aesthetically pleasing designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional suspension systems with pivots and sliding surfaces are used, then suspension function is achieved, but friction and maintenance requirements increase
Solution Approach 1:
The patent replaces traditional mechanical pivot and sliding surface systems with a flexible chainstay design that uses material flexibility and geometric configuration to achieve suspension. The flexible chainstay acts as a compliant element that bends to absorb shocks, eliminating the need for pivots, bearings, and sliding surfaces that require lubrication and maintenance.
Solution Approach 2:
The patent employs a flexible chainstay made from materials and geometries that allow controlled bending and flexing. This flexible element serves as the suspension mechanism, replacing rigid mechanical joints with a compliant structure that naturally absorbs impacts through elastic deformation without friction or wear.
2Adaptability or versatility
If pivots and sliding surfaces are used in suspension systems, then suspension movement is enabled, but weight increases
Solution Approach 1:
The patent eliminates heavy mechanical components such as pivots, bearings, and sliding surfaces by replacing them with a flexible chainstay design. The suspension movement is achieved through the bending flexibility of the chainstay itself, which is significantly lighter than traditional mechanical joint assemblies.
Solution Approach 2:
The flexible chainstay uses thin-walled or optimized cross-section geometries that provide sufficient flexibility for suspension movement while minimizing material usage and weight. The flexible element achieves the required compliance through its geometric design rather than through heavy mechanical joints.
3Reliability
If supplemental suspension units are added, then suspension performance improves, but device complexity increases
Solution Approach 1:
The flexible chainstay performs multiple functions simultaneously: it provides structural support for the rear wheel, enables suspension movement through its flexibility, and transmits driving forces from the chain. This multi-functionality eliminates the need for separate supplemental suspension units, reducing overall system complexity.
Solution Approach 2:
The patent merges the functions of the chainstay and suspension elements into a single integrated component. The flexible chainstay combines structural, suspensive, and force-transmission roles that would traditionally require separate components, thereby simplifying the overall suspension system.
4Reliability
If more suspension components are used, then suspension capability increases, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple suspension functions into a single flexible chainstay component, reducing the total number of parts that need to be manufactured, assembled, and quality-checked. This integration simplifies the manufacturing process while maintaining suspension capability.
Solution Approach 2:
The flexible chainstay can be manufactured using modern composite material techniques or optimized metal forming processes that create the required flexibility and structural properties in a single manufacturing step, reducing assembly complexity compared to traditional multi-component suspension systems.
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 system provides effective vertical suspension with minimal friction, reducing maintenance and weight, while allowing for adjustable stiffness to suit different riding preferences, enhancing performance and comfort.
Implementation Method 1
a leaf spring (111) interconnecting said seatstays and said seat tube, wherein one end of the leaf spring (111) is connected to the upper end area of said seatstays, and wherein the leaf spring (111) extends downwardly from its point of connection to the upper end area of the seatstays to a point of connection to the seat tube of the bicycle
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
A rear wheel suspension system (101) for a bike, comprising a seat tube (104), a bottom bracket shell (106), left and right side flexible chainstays (102;103) and a right side flexible chainstay (103), left and right side seatstays (107;108), and a set of dropouts (110) located where said flexible chainstays and said seatstays interconnect for rotably supporting said rear wheel of said bicycle. A leaf spring (111) interconnects said seatstays and said seat tube, wherein one end of the leaf spring (111) is connected to the upper end area of said seatstays. The leaf spring (111) extends downwardly from its point of connection to the upper end area of the seatstays to a point of connection to said seat tube of said bicycle. The leaf spring is arranged at a distance D to the seat tube in a direction perpendicular to top and bottom surfaces of the leaf spring to allow flex of said leaf spring towards the seat tube and thus vertical flex of said flexible chainstays.