Threaded Chainring Carrier for Interchangeable Power Meter Gears
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Solution Overview
Problem
Bicycle power meter devices face challenges in being adaptable to different chainring configurations while minimizing drive train weight, and existing solutions often require complex assembly and high maintenance costs.
Innovation Solution
A front chainring assembly with a removable chainring structure threadably engaged with a chainring carrier, integrated with a power meter device that includes strain measurement devices and circuitry for power calculation, allowing for easy chainring replacement and reduced weight without sacrificing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a chainring structure is made removable and threadably engaged with the chainring carrier, then chainring interchangeability is improved and weight is reduced, but assembly complexity increases
Solution Approach 1:
The chainring assembly is divided into separable components: a chainring carrier integrated with the power meter device and a removable chainring structure. The chainring structure can be independently removed and replaced by rotating it relative to the carrier, enabling easy interchangeability while keeping the power meter device permanently installed on the crank arm.
Solution Approach 2:
The chainring carrier serves multiple functions: it acts as the mounting interface for the chainring structure, provides the threaded engagement mechanism for removable chainrings, and is integrated with the power meter device body. This multi-functionality reduces the need for separate components and simplifies the overall assembly.
2Strength
If lugs and bolts are used to interface the chainring carrier and chainring structure, then connection strength is improved, but weight increases and assembly time increases
Solution Approach 1:
The traditional lug and bolt interface is completely removed from the chainring-carrier connection. Instead, the chainring structure directly threads onto the carrier via threaded peripheries, eliminating unnecessary components and reducing weight while maintaining secure connection through the threaded engagement.
Solution Approach 2:
The mechanical fastening system (lugs and bolts) is replaced with a threaded engagement system. The chainring structure's inner threaded periphery mates with the carrier's outer threaded periphery, providing a secure connection through screw-thread mechanics rather than discrete fasteners.
3Reliability
If lugs and bolts are used to interface the chainring carrier and chainring structure, then connection reliability is improved, but maintenance cost and assembly time increase
Solution Approach 1:
The multi-step assembly process involving alignment of lugs and insertion of bolts is replaced by a simple threaded engagement. The chainring structure is installed by rotating it onto the carrier until the threads engage and tighten, reducing assembly to a single rotational motion that is both faster and more reliable.
4Weight of moving object
If a threaded engagement system is used between the chainring carrier and chainring structure, then weight is reduced and ease of operation is improved, but manufacturing precision requirements increase
Solution Approach 1:
The carrier's threaded periphery serves as both the connection interface for the removable chainring and an integral part of the power meter device mounting system. This unified threaded design simplifies manufacturing by using a single standardized thread interface for multiple functions, reducing the need for multiple precision features.
Data Source
AI summary
A chainring assembly includes a chainring carrier adapted to be coupled to a crank arm. The chainring carrier is rotatable about a rotation axis, and includes an outer periphery having carrier threads. A chainring structure includes an inner periphery having chainring threads and an outer periphery comprising a plurality of teeth. The inner periphery of the chainring structure is threadably engaged with the outer periphery of the chainring carrier. In one embodiment, a power meter device includes a body having a torque input section and a torque output section, with the torque output section including an outer periphery having threads adapted to be coupled to a chainring structure.