Bicycle Suspension Preload Control Using Piston-Guided Fluid Switching

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Solution Overview

Problem

Existing bicycle suspensions face challenges in adjusting preload accurately and efficiently, with mechanical and air suspensions requiring manual trial-and-error adjustments that are cumbersome and imprecise, often necessitating excessive fluid handling and weight-dependent changes.

Innovation Solution

An adjustable suspension system with a piston mechanism that automatically adjusts preload based on user weight by translating between positions to control fluid communication, allowing precise and quick preload setting through fluid injection and evacuation without manual intervention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If manual trial-and-error pressure adjustment is used, then preload can be adjusted, but the adjustment process becomes long and tedious

Engineering Contradiction:
Improvepreload adjustment processVSAvoidadjustment time
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The patent implements a feedback mechanism where the piston's position (determined by user weight) automatically controls the valve device state. When the piston moves to a certain position under user weight, it triggers the valve to switch states, enabling automatic preload adjustment based on real-time feedback from the suspension compression state.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The suspension system performs self-adjustment of preload based on user weight. The piston automatically moves according to the compression force from user weight, and this movement automatically controls the valve device to regulate fluid pressure, eliminating the need for manual trial-and-error adjustment.

Inventive Principle:
Principle #25Self-service

2Stress or pressure

If excessive fluid is injected into the suspension, then preload can be increased, but manual fluid extraction becomes necessary

Engineering Contradiction:
Improvefluid pressureVSAvoidfluid management
Core Design Contradiction:
Stress or pressureVSEase of operation

Solution Approach 1:

The valve device receives feedback from the piston position and automatically switches between injection and extraction modes. When the piston reaches a predetermined position indicating sufficient preload, the valve automatically switches from injection mode to extraction mode, preventing over-injection and eliminating manual fluid management.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The valve device operates in periodic cycles of fluid injection and extraction based on piston position feedback. The system automatically alternates between injecting fluid to increase pressure and extracting fluid to reduce pressure, creating a self-regulating periodic action that maintains optimal preload.

Inventive Principle:
Principle #19Periodic action

3Adaptability or versatility

If mechanical springs are used for suspension, then preload adjustment is possible, but the spring weight increases significantly

Engineering Contradiction:
Improvepreload adjustabilityVSAvoidspring weight
Core Design Contradiction:
Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent replaces mechanical springs with a pneumatic/hydraulic system using fluid pressure to provide suspension force. Fluid is injected into a chamber to create pressure that supports the user weight, eliminating the need for heavy mechanical springs while maintaining preload adjustability through fluid pressure control.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The system adjusts preload by changing fluid pressure parameters rather than changing mechanical spring properties. By controlling the pressure of the injected fluid, the system can easily adjust preload for different user weights without replacing physical components, significantly reducing overall system weight.

Inventive Principle:
Principle #35Parameter changes

4Productivity

If user estimates preload satisfaction manually, then adjustment can be completed, but precision and accuracy are compromised

Engineering Contradiction:
Improveadjustment speedVSAvoidpreload accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The system uses feedback from the piston's actual position under user weight to automatically determine when optimal preload is achieved. The piston position serves as an objective measurement indicator, replacing subjective user estimation with precise mechanical feedback that triggers automatic valve switching.

Inventive Principle:
Principle #23Feedback

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

Enables rapid, precise, and weight-dependent preload adjustment, eliminating the need for manual trial-and-error, reducing fluid consumption, and ensuring consistent preload settings without excessive pressure changes.

Implementation Method 1

the piston being configured to move from the first position to the second position when fluid is injected through the main fluid inlet

Methodology Applied
Scientific EffectFluid pressure: Pressure Increase

Implementation Method 2

a valve device capable of assuming a first state in which it prevents fluid from escaping from the suspension, and a second state in which it allows extraction of the fluid from the suspension

Methodology Applied
Scientific EffectValve control: Valve

Data Source

PatentEP3942194B1Adjustable suspension for a bicycle
Publication Date: 2025.08.13 DECATHLON SA
  • EP3942194B1 patent drawingFigure 1
  • EP3942194B1 patent drawingFigure 2
  • EP3942194B1 patent drawingFigure 3

AI summary

Adjustable suspension (10) for a bicycle, comprising a suspension body (12) provided with a main fluid inlet (31) and a fluid outlet (32), a piston (14) that is disposed in the suspension body and comprises a piston head (26) delimiting a first chamber (28) and a second chamber (30), the first chamber being fluidically connected to the main fluid inlet, the piston being able to move in translation in the suspension body between at least one first position, in which the fluid outlet is fluidically connected to the second chamber but not to the first chamber, so as to deploy the piston, and at least one second position, in which the fluid outlet is fluidically connected to the first chamber.