Modular Bicycle Crankset With Single-Screw Quick Replacement
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Solution Overview
Problem
Existing modular crankset systems are complex to assemble and disassemble, often requiring removal of all bicycle elements and can result in damage to screws or fitting wheels, and may cause lateral play and chain-line deviations due to crimping processes.
Innovation Solution
A modular crankset design where the gear wheel and crank are fixed to the crankset shaft with a single screw and a retaining element, allowing for easy replacement without removing the chain, and utilizing a shared interface on the shaft to eliminate lateral play and simplify assembly, with CNC machining ensuring high accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If modular crankset systems use screws or fitting wheels to fix elements, then assembly and disassembly can be performed, but the screws or fitting wheels tend to get damaged with repeated exchanges
Solution Approach 1:
The patent replaces the traditional screw-based mechanical fastening system with a crimping system that uses a crimping tool to deform the crank arm and lock it to the spider. This substitution eliminates the need for reusable fastening components like screws, thereby preventing their damage from repeated assembly and disassembly operations.
Solution Approach 2:
The patent employs a disposable approach where the crank arm itself is deformed to create the locking mechanism. The crimping process permanently deforms the crank arm material to lock the assembly, making the crank arm structure itself the fastening element rather than a separate reusable component.
2Ease of manufacture
If crimping process is used to fix spider to crank, then connection is achieved, but lateral play on the chain ring occurs due to incomplete alignment
Solution Approach 1:
The patent incorporates preliminary alignment features in the form of positioning protrusions and recesses that guide the spider and crank arm into correct alignment before the crimping operation. This preliminary positioning ensures that the components are properly aligned prior to the deformation process, preventing lateral play in the final assembly.
Solution Approach 2:
The patent introduces positioning protrusions and recesses as intermediary alignment features that mediate between the spider and crank arm. These features act as mechanical guides that ensure precise alignment during the assembly process, eliminating the misalignment problems that occur with direct crimping.
3Ease of manufacture
If crimped connection is used between shaft and crank, then fixation is achieved, but deviation on the chain-line occurs
Solution Approach 1:
The patent implements preliminary positioning features including positioning protrusions on the shaft and corresponding recesses on the crank arm that establish correct chain-line alignment before the crimping operation occurs. This pre-alignment prevents chain-line deviation in the final assembled state.
Solution Approach 2:
The patent employs asymmetric positioning features with specific geometric configurations that are designed to accommodate the chain-line requirements. The positioning protrusions and recesses have asymmetric shapes that guide the components into the correct relative positions, ensuring proper chain-line alignment while allowing the crimping connection to be formed.
4Strength
If traditional crankset elements are fixed together, then structural integrity is maintained, but replacement of elements requires long stops and complex procedures
Solution Approach 1:
The patent divides the crankset into separable modular components including the crank arm, spider, and chain ring that can be independently replaced. The crimping connection allows for relatively quick release and reattachment of these segments, enabling partial replacements without requiring disassembly of the entire crankset assembly.
Solution Approach 2:
The patent creates a dynamic fastening system where the crimping connection can be quickly released and reformed using a crimping tool. This allows the crankset components to transition between locked and unlocked states efficiently, enabling rapid replacement of worn or damaged elements without lengthy disassembly and reassembly procedures.
Data Source
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AI summary
The present patent application describes a modular crankset for bicycles. The described modular crankset is useful for users, since it solves issues related to the speed of replacement of elements, the easiness of the replacement procedures and lowers the weight of the set without compromising the consistency and rigidity of the set. The current technology is applicable to any bicycle available in the market, including electrical bicycles, and it is especially interesting for competition bicycles, wherein the replacement of the constituent elements of the crankset should be made as quickly as possible.