Segmented Bicycle Chain-Rings for Smooth Shifting Without Derailleurs

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Solution Overview

Problem

Current bicycle transmission systems with derailleurs face inefficiencies and reliability issues due to high friction, wear, and the need for significant force to shift chain-rings, leading to incomplete power transmission and potential chain slippage, especially with non-round chain-rings.

Innovation Solution

A segmented chain-ring system where the second chain-ring is formed by independent up-shift and down-shift segments with specific angular arrangements, allowing for efficient power transmission without derailleurs, by ensuring optimal engagement and reducing the seating phase III through tangential force transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If derailleurs are used to displace the chain between chain-rings, then gear shifting is enabled, but friction and wear increase significantly

Engineering Contradiction:

Improvegear shifting capabilityVSAvoidfriction and wear

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent removes the derailleur component entirely from the system. Instead of using a derailleur to push the chain laterally between chain-rings, the invention uses a non-round chain-ring geometry that allows the chain to transition between different chain-rings through its own tension and the geometric profile of the chain-ring teeth, eliminating the need for pushing elements and thereby reducing friction and wear.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of actively pushing the chain from one chain-ring to another using a derailleur, the invention inverts the approach by designing the chain-ring itself with a non-round profile that passively guides the chain through its tension and geometric shape, allowing the chain to follow the contour and transition naturally without external forcing.

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If the chain is displaced laterally by the derailleur, then shifting between chain-rings occurs, but chain slippage and instability increase

Engineering Contradiction:

Improvechain displacement capabilityVSAvoidchain stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent employs a non-round chain-ring profile where the radius varies angularly around the chain-ring. This curvature variation creates zones of different engagement characteristics that guide the chain smoothly from one chain-ring to another, improving stability by ensuring continuous contact and proper alignment during the transition, eliminating slippage associated with lateral pushing.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Adaptability or versatility

If multiple chain-rings with different sizes are combined, then multiple transmission ratios are obtained, but the complexity of the transmission system increases

Engineering Contradiction:

Improvetransmission ratio rangeVSAvoidtransmission system complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The non-round chain-ring design serves multiple functions simultaneously: it provides the primary transmission ratio variation through its variable radius profile, enables smooth chain transition between different effective radii without derailleurs, and maintains chain stability through its geometric profile. This multi-functionality reduces overall system complexity despite offering multiple transmission ratios.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

This solution enables smooth, precise, and reliable shifting with reduced wear and friction, maintaining optimal power transmission across a wide range of gear ratios, even with non-circular chain-rings, and supports the chain better against vibrations.

Implementation Method 1

Current bicycle transmission systems with derailleurs face inefficiencies and reliability issues due to high friction, wear, and chain slippage during gear shifts

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

A segmented chain-ring system where the second chain-ring is formed by independent up-shift and down-shift segments with specific angular arrangements, allowing for efficient power transmission and smooth shifting without derailleurs, by ensuring optimal engagement and reduced seating phase III through tangential force transmission

Methodology Applied

Scientific EffectTangential force transmission: Friction

Data Source

PatentUS20210031878A1Chain-rings set for a bicycle power transmission system provided with segmented chain-ring and segmentation method for obtaining it

Publication Date: 2021.02.04 ZUMA INNOVATION SL

AI summary

Chain-rings sets for power transmission systems, where at least one of the chain-rings is formed by independent segments provided with axial displacement means, where the segmentation is optimum both for shifts to a bigger chain-ring or a smaller chain-ring through a relative configuration between chain-rings, especially between the teeth involved in the power transmission during the shift, that ensure a smooth shift, efficient in the power transmission and reducing as possible the friction and the wear of the components.