Mountain Bike Rim Hollow Chamber Segmentation
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Solution Overview
Problem
Mountain bike rims with large widths face challenges in stability and weight, particularly when using tubeless tires, due to interaction with spoke nipples that can lead to defects.
Innovation Solution
A double-walled rim design with a hollow chamber and recesses on the rim base, allowing for spoke nipples to be positioned within the rim body, providing stability and reducing weight while accommodating tubeless tires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the rim width is increased to accommodate wider mountain bike tires, then the tire stability and traction are improved, but the rim weight increases significantly
Solution Approach 1:
The rim is divided into an outer rim wall and an inner rim wall that are not fully connected, creating a hollow chamber between them. This segmentation allows material to be removed from the rim structure while maintaining structural integrity, significantly reducing rim weight while preserving the stability needed for wide mountain bike tires
Solution Approach 2:
The inner rim wall is nested within the outer rim wall, creating a hollow chamber structure. This nested configuration allows the rim to maintain its external dimensions for tire stability while removing internal material to reduce weight, effectively solving the contradiction between width/stability and weight
2Weight of moving object
If a single-walled rim with punched-out areas is used to reduce weight, then the rim weight is reduced, but the reliability for tubeless tire operation deteriorates due to spoke nipple interaction with the tire
Solution Approach 1:
The rim is segmented into outer and inner walls with a hollow chamber between them, creating a physical barrier that isolates spoke nipples from the tire. This segmentation prevents the reliability issues associated with single-walled rims while maintaining weight reduction benefits
Solution Approach 2:
The hollow chamber acts as an intermediary space between the spoke nipples and the tire, preventing direct interaction between them. This intermediary structure eliminates the harmful interaction that causes tubeless tire defects while preserving the lightweight design
3Stability of the object's composition
If a double-walled rim structure is used to improve stability, then the rim stability is improved, but the rim weight increases
Solution Approach 1:
The double-walled structure is segmented with a hollow chamber between the outer and inner walls, removing material that would otherwise increase weight. This segmented approach maintains the stability benefits of a double-walled construction while minimizing weight through strategic material removal
Solution Approach 2:
The rim structure has varying wall thicknesses and material distribution - thicker walls where structural support is needed and thinner or absent walls in the hollow chamber region. This local quality variation provides stability where required while minimizing overall weight
Data Source
Figure 1~3
Figure 4~5c
Figure 6~11
AI summary
A rim (1) for a mountain bike comprising a rim body (2) with a rim bed (3), a rim base (4), two lateral rim flanges (5, 6), and a hollow chamber assembly (7) with a hollow chamber (8). The hollow chamber assembly (7) of the rim body (2) is bounded radially outwards by the rim bed (3) and laterally and radially inwards by an inner boundary wall (9) comprising the rim base (4) and the rim flanges (5, 6). A width (22) of the rim body (2) is greater than 30 mm. The radially inner boundary wall (9) forms a substantially closed inner wall, except for the spoke nipple recesses (12). The rim bed (3) has a plurality of recesses (10, 11) with a surface area of at least 10% of a surface (13) of the rim bed (3).