Single-Sprocket Chain Guide for Virtual Shifting Bicycle Trainers

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Solution Overview

Problem

Existing bicycle trainer systems require users to manually install and switch cassettes, leading to complexity and wear on bicycles, especially when multiple users or different bikes are involved, and physical gear shifting can interfere with virtual shifting mechanisms.

Innovation Solution

A single-sprocket system for bicycle trainers that allows easy installation without tools, featuring a gully and guide design to keep the chain aligned, preventing accidental disengagement during physical shifting, and providing virtual gear shifting through electronic resistance adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple cassettes are used to accommodate different bicycles and users, then the trainer can serve more users and bikes, but the complexity of installation and cassette switching increases

Engineering Contradiction:
Improvecompatibility with different bicyclesVSAvoidcassette installation complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts the cassette from the system entirely, replacing it with a single fixed sprocket. This eliminates the need to install different cassettes for different bicycles, while the chain guide ensures proper chain routing on the single sprocket, thereby reducing installation complexity while maintaining versatility

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The single sprocket is designed to work with bicycles of different wheel sizes (26-inch, 29-inch, and 700c) through an adjustable chain guide mechanism. This universal design allows one sprocket to serve multiple functions that previously required multiple cassettes, simplifying the system while maintaining adaptability

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Ease of operation

If physical gear shifting is allowed, then users can change gears during riding, but accidental disengagement and wear on bicycle components occur

Engineering Contradiction:
Improvegear shifting capabilityVSAvoidchain engagement stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent removes the traditional derailleur and multiple cassettes, replacing them with a single fixed sprocket and chain guide system. This extraction of the physical gear shifting mechanism eliminates accidental disengagement issues while maintaining operational ease through the chain guide's ability to control chain position

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The chain guide acts as an intermediary between the chain and the single sprocket, ensuring proper chain routing and preventing disengagement. This intermediary component provides the gear shifting function through controlled chain positioning rather than physical derailleur movement, improving reliability while maintaining ease of operation

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If traditional cassette systems are used, then gear variations are achieved, but noise and wear on bicycle components increase

Engineering Contradiction:
Improvegear ratio variationVSAvoidnoise and component wear
Core Design Contradiction:
Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the cassette and derailleur components from the system, replacing them with a single fixed sprocket and chain guide. This eliminates the mechanical complexity that causes noise and wear, while gear ratio variation is achieved through alternative means (electronic resistance adjustment or flywheel inertia changes) rather than physical gear changes

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical cassette and derailleur system with a single sprocket system where gear variation is achieved through non-mechanical means such as electronic resistance adjustment or flywheel inertia modification. This substitution eliminates the noise and wear associated with traditional mechanical gear shifting while maintaining the ability to vary effective gear ratios

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP4205825B1Single-sprocket system for a bicycle trainer
Publication Date: 2025.11.05 ZWIFT INC
  • EP4205825B1 patent drawingFigure 1
  • EP4205825B1 patent drawingFigure 2~3
  • EP4205825B1 patent drawingFigure 4

AI summary

A single-sprocket system for integration into a bicycle trainer, the system including a sprocket having teeth about a perimeter of the sprocket, a first planar side, and a second planar side, wherein the teeth of the sprocket are configured to engage a chain of a bicycle mounted to the bicycle trainer. The system further includes a first chain guide adjacent the first planar side of the sprocket, wherein the first chain guide is configured to re-engage the teeth of the sprocket with the chain when the chain has become disengaged from the teeth of the sprocket towards the first planar side, and a second chain guide adjacent the second planar side of the sprocket, wherein the second chain guide is configured to re-engage the teeth of the sprocket with the chain when the chain has become disengaged from the teeth of the sprocket towards the second planar side.