Cross Frame Tube Geometry for E-Bike Torsional Rigidity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing cross frames for bicycles, particularly e-bikes, lack stability and torsional rigidity, making them unsuitable for e-bikes and aesthetically unappealing, with limited adaptability to riders of varying inseam lengths.
Innovation Solution
A cross frame design featuring a straight first tube crossing the seat tube and splitting towards the rear dropout, with a second tube angled above the head tube intersecting the first tube and extending to the bottom bracket area, incorporating a single or dual chainstay configuration, and a widened step-through area for improved stability and ease of use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a traditional cross frame design is used, then the frame has a simple structure and elegant appearance, but it lacks stability and torsional rigidity
Solution Approach 1:
The frame is divided into multiple functional tubes: a first tube forming the main cross frame structure, a second tube providing additional stability, and a third tube enhancing torsional rigidity. Each tube segment serves a specific structural purpose while maintaining the overall elegant cross frame appearance.
Solution Approach 2:
The patent employs composite material construction for the frame tubes, combining different materials or material configurations to achieve both aesthetic elegance and structural stability. This allows the frame to maintain slender, elegant lines while incorporating reinforcement elements for improved rigidity.
2Device complexity
If a traditional cross frame design is used, then the frame has a simple structure, but it lacks torsional rigidity
Solution Approach 1:
The frame structure is segmented into three main tubes with distinct functions: the first tube provides the primary structural framework, the second tube specifically addresses stability requirements, and the third tube targets torsional rigidity enhancement. This segmentation allows each component to be optimized for its specific function while maintaining overall structural simplicity.
Solution Approach 2:
The patent introduces tubes with bends in different spatial dimensions. The second tube has a bend in the frame plane, while the third tube extends in directions that add dimensional complexity to resist torsional forces. This multi-dimensional tube arrangement enhances torsional rigidity without significantly increasing structural complexity.
3Shape
If the bottom bracket area is positioned traditionally, then the frame maintains standard geometry, but the step-through area is narrow and climbing on is difficult
Solution Approach 1:
The bottom bracket area is dynamically repositioned toward the front wheel, creating a more open step-through geometry. This dynamic repositioning allows riders to more easily mount and dismount the bicycle while maintaining the essential cross frame geometric characteristics. The shifted bottom bracket also creates additional space in the step-through area for rider comfort.
Data Source
Figure 1
Figure 2a~2b
AI summary
The invention relates to a cross frame for a bicycle comprising a head tube and a seat tube with a bottom bracket area arranged at the lower end of the seat tube, a straight first tube attached to the head tube, which crosses the seat tube and then extends towards the rear dropout, and a second tube attached to the head tube above the first tube, which crosses the first tube at an intersection and then extends to the bottom bracket area.In order to create a cross frame for a bicycle, in particular an e-bike, which is visually appealing, has high stability and torsional rigidity with the lowest possible weight and allows improved handling of a bicycle equipped with the frame, it is proposed that the second tube in the section between the head tube and the intersection has an angle lying in the frame plane, at least one chainstay extends from the bottom bracket area to the rear triangle dropout and the cross frame has exclusively the head tube, the seat tube, the first and second tube and the at least one chainstay.