Composite Bicycle Crank Spindle Interface for Lightweight Assembly
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing manufacturing processes for bicycle cranks require separate and different manufacturing methods for left and right crank arms, leading to increased time and cost, and necessitate different attachment methods, which complicates the production of lightweight and strong crank sets.
Innovation Solution
A composite bicycle crank with an integral spindle attachment structure allows for the separate manufacturing of crank arms and spindles or inserts from different materials, using interfaces such as round lobed splines, circular, or tapered interfaces, and then securely attaching them, enabling a lighter and stronger assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate manufacturing processes are used for left and right crank arms, then each crank arm can be optimized for its specific function, but manufacturing time and cost increase
Solution Approach 1:
The crank arm is divided into two separate components: a crank arm body and a crank arm insert. This segmentation allows each component to be manufactured independently using optimized processes for their specific materials and functions, then assembled together. The insert can be manufactured with precision features for spindle attachment while the crank arm body can be optimized for strength and aerodynamics, resolving the contradiction between functional optimization and manufacturing efficiency.
2Adaptability or versatility
If different attachment methods are used for left and right crank arms, then each can be optimized for its specific loading conditions, but device complexity increases
Solution Approach 1:
The crank arm insert is designed as a universal component that can be used in both left and right crank arms. The insert contains the spindle attachment features and can be manufactured in left-handed or right-handed configurations. This universal design allows the same basic insert geometry to serve both crank arms, reducing device complexity while maintaining the ability to optimize attachment for each specific loading condition through the orientation and configuration of the spline interfaces.
3Weight of moving object
If crank arms are made from lightweight materials, then overall crank set weight decreases, but attachment strength and reliability may be compromised
Solution Approach 1:
The crank arm assembly uses a composite construction combining a lightweight crank arm body (made from materials such as carbon fiber reinforced polymer) with a dense crank arm insert (made from high-strength metal such as aluminum alloy or titanium). This composite approach allows the majority of the crank arm to be lightweight while the critical attachment region in the insert provides the necessary strength and reliability for spindle connection, effectively resolving the contradiction between weight reduction and attachment reliability.
4Ease of manufacture
If integral crank arms with built-in spindle attachment are manufactured, then manufacturing steps are reduced, but material selection and weight optimization are limited
Solution Approach 1:
By separating the crank arm into a body and an insert component, the invention enables each component to be manufactured using the most appropriate process and material for its specific requirements. The crank arm body can be manufactured using composite material processes (such as resin transfer molding or autoclave curing) while the insert can be manufactured using metal forming or machining processes. This segmentation maintains manufacturing simplicity while dramatically increasing material selection flexibility compared to trying to create an integral crank arm with built-in attachment features.
Data Source
AI summary
A composite bicycle crank with an integral spindle attachment structure provides a unique method for attaching a bicycle crank arm to a bicycle crank spindle, and also for attaching a bicycle crank arm to a crank arm insert. A light-weight crank arm is able to be manufactured separately from the crank spindle or insert, and then securely attached after both pieces have been made. This allows for the pieces of the crank assembly to be manufactured from one or more different materials, and securely connected after manufacturing, to create a lower weight assembly than would be possible otherwise.