Bicycle Stem Frustoconical Clamping for Continuous Adjustment
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Solution Overview
Problem
Existing cycle stems with adjustable inclination suffer from slippage issues and require high tightening torque, leading to discontinuous angle adjustments and increased weight and complexity.
Innovation Solution
A cycle stem design utilizing frustoconical bodies with a low taper angle of approximately 10° and a connection mechanism involving screws and a double-pitch screw for continuous adjustment without slippage, ensuring secure clamping and reduced torque requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clamping means with notches are used to block the stem in angular positions, then the stem can be locked in chosen inclination, but continuous adjustment is impossible and the adjustment is made with steps of 3 degrees giving a difference in height of 3 to 5 mm per notch
Solution Approach 1:
The invention changes the geometric parameters of the clamping surfaces by using conical surfaces with a specific taper angle (15-30 degrees) instead of cylindrical surfaces with notches. This parameter change enables continuous adjustment while maintaining reliable locking through friction-based clamping, eliminating the discrete 3-degree steps of prior art.
Solution Approach 2:
The invention applies curved conical surfaces instead of flat or notched cylindrical surfaces. The conical shape with its gradual curvature allows for smooth, continuous angular adjustment while the friction between the conical clamping surfaces provides reliable locking without requiring notches or discrete positions.
2Reliability
If a large central screw is used to bias frustoconical projections together, then binding ability is based on friction, but the tightening torque required is high and the structure becomes more complex
Solution Approach 1:
The invention segments the clamping function into two separate conical bodies (first and second conical bodies) that clamp the pivot tube from opposite sides. This segmentation distributes the clamping force and eliminates the need for a single large central screw, reducing both the tightening torque requirement and structural complexity while maintaining reliable friction-based binding.
Solution Approach 2:
The invention uses asymmetric conical surfaces with a specific taper angle (15-30 degrees) that are not symmetric about the central axis. This asymmetric geometry allows the conical bodies to self-align and provides efficient mechanical advantage, reducing the tightening torque needed compared to symmetric frustoconical projections requiring a large central screw.
3Ease of operation
If frustoconical projections with taper angle less than 15° are used, then continuous adjustment is enabled, but jamming of the projections occurs
Solution Approach 1:
The invention employs asymmetric conical surfaces with a taper angle of 15-30 degrees that prevents jamming through proper geometric design. The specific angular range and asymmetric configuration allow continuous adjustment while maintaining reliable operation by preventing the projections from binding or jamming during rotation.
Solution Approach 2:
The invention optimizes the taper angle parameter to a specific range (15-30 degrees) that balances continuous adjustability with jamming resistance. This parameter optimization, combined with the conical geometry, enables smooth continuous adjustment while preventing the projections from jamming, unlike smaller taper angles that cause jamming issues.
4Reliability
If anti-slip washers and large screws are added to prevent slippage, then the joint can support high tightening torque, but the device becomes more complicated and heavier
Solution Approach 1:
The invention extracts and eliminates the need for additional anti-slip washers and large screws by integrating the slippage prevention function directly into the conical clamping mechanism. The friction-based clamping between the conical bodies and pivot tube provides inherent anti-slip capability, reducing the overall weight by removing unnecessary components.
Solution Approach 2:
The invention merges the clamping function and the anti-slip function into a single integrated conical clamping mechanism. The friction between the conical surfaces simultaneously provides both the clamping force for positioning and the anti-slip capability, eliminating the need for separate anti-slip washers and reducing the overall weight of the assembly.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables continuous and precise adjustment of the stem inclination without slippage, reducing weight and complexity while maintaining rigidity, allowing for precise handlebar positioning.
Implementation Method 1
Binding ability is based on friction
Implementation Method 2
the invention takes advantage of the wedging of conical shapes to solidly block the pivot
Data Source
Figure 1~4
Figure 5~7
Figure 8~10
AI summary
A stem includes a stem body, one of the extremities of which includes element for attaching a handlebar, the opposite extremity including two parallel arms connected to a pivot tube by an articulation associated with clamping element which immobilize the stem in a chosen position. The clamping element includes a pair of frustoconical bodies connected to the extremities of the arms. The frustoconical bodies are received in housings of complementary shape. The frustoconical bodies are connected by a connecting element capable of moving them closer to one another in order to clamp them in the respective housing, and of loosening them by moving them further apart one from the other so as to allow the continuous adjustment of the inclination of the handlebar. The cone angle of the frustoconical bodies possesses a sufficiently low value to permit them to be pinched inside their housings.