Bicycle Saddle Snap-Fit Rail Assembly With Cam Stress Control

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Solution Overview

Problem

Existing bicycle saddle assembly methods subject the shell and rails to significant stresses, leading to failure and plastic deformation, and previous solutions with flexible supports have weak holding forces, compromising safety.

Innovation Solution

A bicycle saddle structure with a cam connection member that gradually applies tensile stress to the shell and compresses the rails, preventing impulsive stress transfer during assembly, using a snap-fit mechanism without special tools.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the rails are forced into the seat using a special tool with ramp and compressive load, then the shell/rails connection is stabilized, but the shell and rails are subjected to considerable stresses causing failure and plastic deformation

Engineering Contradiction:

Improveconnection stabilityVSAvoidstructural integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

Instead of forcing the rails into the seat using compressive stress, the invention inverts the approach by using the elastic recovery of the rails (which were pre-deformed) to push themselves into the seat. The rails are elastically deformed in a jig, then released to naturally spring into the shell seat, converting the problem from applying external compressive force to utilizing internal elastic energy.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The invention introduces a special jig as an intermediary device that performs the elastic deformation of the rails before assembly. The jig temporarily holds the rails in a pre-deformed state, then releases them to self-assemble into the shell, mediating between the manufacturing process and the final assembly without requiring direct forcing of the rails into the seat.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the rails are released after reaching the lower limit of the ramp, then the connection is stabilized, but the elastic energy transforms into kinetic energy causing impulsive blows to the shell

Engineering Contradiction:

Improveconnection stabilizationVSAvoidimpulsive stress

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention applies preliminary elastic deformation to the rails in a special jig before the actual assembly process. By pre-deforming the rails elastically and then releasing them, the elastic energy is controlled and directed to gently push the rails into the seat, rather than allowing uncontrolled elastic recovery that would create impulsive blows to the shell.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If a flexible support with screw connection is used to secure rails to the shell, then assembly is quick and simple, but the holding force is weak and may lead to disconnection during riding

Engineering Contradiction:

Improveassembly simplicityVSAvoidconnection strength

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention replaces the mechanical screw connection system with an elastic deformation-based self-locking system. Instead of using threads and fasteners that create weak holding points, the rails are elastically deformed and then released to naturally lock into the shell seat through their own elastic recovery, creating a stronger and more reliable connection without complex mechanical fastening components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Ensures a strong, lightweight saddle with improved flexural strength and safety by avoiding impulsive stress, allowing quick and simple assembly without tooling, and enhancing the structural integrity of the shell and rails.

Implementation Method 1

the shell is introduced in a special tool that is operable to cause temporary elongation thereof and then sliding of the front portion of the rails along a ramp

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

the forced sliding motion of the rails along the ramp is caused by a predetermined load operating thereon to cause the required compressive deformation

Methodology Applied

Scientific EffectStress transfer: Mechanical Force

Data Source

PatentUS8371649B2Bicycle saddle structure and method of assembly thereof

Publication Date: 2013.02.12 SELLE ROYAL SPA

AI summary

A bicycle saddle structure includes a load-bearing shell having an elongate front portion, a widened rear portion and a bottom surface with a front seat and a rear seat which are formed at a predetermined minimum distance (dMu\l) therebetween, rails with a rear end portion, and a front end portion which is designed to interact with the front seat of the shell. The rails have a maximum longitudinal extension (Ir) longer than the predetermined minimum distance (dMu\l) between the seats. The structure includes a cam linkage member which is designed to be interposed between the front seat of the shell and the front portion of the rails to cause the shell to be snap fitted to the rails. A method of assembly of the above bicycle saddle structure is also provided.