Bicycle Sprocket Assembly Axial Spacing Design
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Solution Overview
Problem
Conventional bicycle rear sprocket assemblies face limitations in accommodating an increased number of sprockets due to space constraints in the rear frame, making it difficult to enhance gear options without altering the frame dimensions.
Innovation Solution
A bicycle sprocket assembly design that includes a first and second sprocket with specific tooth configurations and axial spacers, allowing for the mounting of additional sprockets on a conventional nine-speed freewheel by using axial spacers to provide spacing without intervening sprockets, thereby increasing the number of gears without altering the frame dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of sprockets is increased to provide more gear options, then the gear variety is improved, but the space required on the rear wheel increases
Solution Approach 1:
The patent transitions from a single-plane sprocket arrangement to a multi-layer configuration where sprockets are stacked axially on the freewheel. This dimensional change allows multiple sprockets to occupy the same radial space at different axial positions, thereby increasing gear variety without proportionally increasing the overall space footprint on the rear wheel.
Solution Approach 2:
The patent implements a nested structure where multiple sprockets are stacked one on top of another on the freewheel axis. This nesting approach allows the sprockets to share the same mounting space on the freewheel, enabling multiple gear options within a compact configuration that fits within conventional frame dimensions.
2Quantity of substance
If sprockets are made thinner to fit more on the rear wheel, then the number of sprockets is improved, but the chain spacing requirement becomes difficult to accommodate
Solution Approach 1:
By stacking sprockets in the axial dimension rather than spreading them out radially, the patent maintains adequate chain spacing in the radial plane while increasing the total number of sprockets. The chain engages with sprockets in a sequential manner as it moves along the axial direction, preserving proper chain geometry and spacing.
Solution Approach 2:
The patent divides the sprocket assembly into multiple discrete layers or stages, with each layer containing one or more sprockets at specific axial positions. This segmentation allows the chain to engage with individual sprockets in a controlled sequence, maintaining proper chain spacing and engagement geometry while accommodating multiple sprockets on the freewheel.
3Adaptability or versatility
If more sprockets are mounted on the rear hub assembly, then the gear options are improved, but the conventional bicycle frame space is exceeded
Solution Approach 1:
The patent nests multiple sprockets on the existing freewheel structure, utilizing the available axial space on the rear hub assembly. This nested configuration allows multiple gears to be mounted within the constraints of conventional frame dimensions by stacking sprockets rather than expanding the overall footprint.
Solution Approach 2:
The patent exploits the axial dimension of the freewheel to mount additional sprockets, thereby increasing gear options without increasing the radial or lateral dimensions that would conflict with conventional frame designs. This dimensional approach allows the sprocket assembly to fit within existing frame constraints while providing more gear variety.
Data Source
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AI summary
A bicycle sprocket assembly is provided with at least a first sprocket, a second sprocket and a first axial spacer. The first sprocket includes an outermost peripheral portion defining a plurality of first teeth, and an innermost peripheral portion defining an opening that is free of any freewheel engaging splines. The first sprocket is larger than any other sprocket of the bicycle sprocket assembly. The second sprocket includes an outermost peripheral portion defining a plurality of second teeth, and an innermost peripheral portion defining an opening having a plurality of freewheel engaging splines. The first axial spacer is fixed to the first and second sprockets such that the first axial spacer is disposed between the first and second sprockets without any intervening sprockets disposed between the first and second sprockets. The first axial spacer includes an innermost peripheral portion defining an opening having a plurality of freewheel engaging splines.