Double Bridge Fork Internal Cable Routing
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Solution Overview
Problem
Current bicycle frames with double bridge forks for racing and time trial machines face aerodynamic inefficiencies due to cable routing issues, particularly turbulence caused by cables guided past the head tube and the placement of front wheel brakes, which impairs air flow and increases drag.
Innovation Solution
The bicycle frame design features a double-bridge fork with a fork crown connected to a lower bearing mount inserted into the head tube from below, allowing activation elements to be routed internally through the steerer tube and stem, avoiding external emergence and thus minimizing turbulence. This design keeps cables and hydraulic lines within the frame, improving aerodynamics by eliminating external elements that cause air turbulence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cables are routed laterally next to the head tube and inserted into the down tube from below or from the side, then the cables can be laid within the frame, but turbulence occurs and aerodynamics deteriorate
Solution Approach 1:
The patent extracts the cables from the traditional lateral routing path next to the head tube and relocates them to run through the steerer tube interior. This removes the harmful lateral cable segments that cause turbulence, while maintaining the benefit of cables being laid within frame components.
Solution Approach 2:
The patent changes the routing dimension by moving cables from lateral routing (side-to-side) to longitudinal routing (front-to-back) through the steerer tube. This dimensional change allows cables to follow the direction of air flow rather than crossing it, eliminating turbulence.
2Ease of operation
If the front wheel brake is arranged in front of the double bridge bicycle fork in the direction of travel, then the brake can be positioned for effective braking, but considerable air turbulence occurs and aerodynamics are greatly impaired
Solution Approach 1:
The patent extracts the brake from its traditional position in front of the fork and relocates it to the rear of the fork crown. This removes the brake from the direct path of air flow, eliminating the harmful turbulence while preserving braking functionality through alternative positioning.
3Object-affected harmful factors
If the front wheel brake is arranged on the rear of the fork crown, then aerodynamics are improved, but the brake cable is arranged laterally next to the control tube and aerodynamics deteriorate
Solution Approach 1:
The patent merges the brake cable routing with the existing control tube interior space. Instead of creating a separate lateral cable path, the brake cable is integrated into the control tube routing, eliminating lateral cable segments and maintaining clean aerodynamic lines.
4Stability of the object's composition
If a direct connection between the lower bearing mount and upper bearing mount is provided, then structural stability is achieved, but activation elements cannot be inserted from between the bearing mounts
Solution Approach 1:
The patent segments the bearing mount connection by introducing an intermediate connection element between the lower and upper bearing mounts. This segmentation creates an accessible opening for activation element installation while maintaining structural stability through the intermediate connector.
Data Source
Figure 1~2
Figure 3
AI summary
A double-crown bicycle fork with an integrated brake unit, particularly suitable for racing bikes and time trial machines, has two fork legs (26) connected to each other via a fork crown (24). A lower bearing mount (22) is also connected to the fork crown (24). A steerer tube (28) is provided in the direction of travel in front of the fork's axis of rotation, which is defined by the lower bearing mount (22) and the upper bearing mount (34). This steerer tube is connected to the stem (32) via screws (42). This design eliminates the need for a rigid head tube between the two bearing mounts (22, 32). Instead, in the illustrated embodiment, a sleeve (16) is used, which has an opening (17) for guiding activation elements (14), such as shift or brake cables, through it.