Bicycle Hub Freewheel Axial Segmentation
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Solution Overview
Problem
Existing bicycle hubs with freewheel mechanisms face issues such as increased weight, reduced durability due to high loads, and alignment errors during maintenance, which affect the wheel's centering and overall performance.
Innovation Solution
A hub design featuring a freewheel device with two interacting components, a hub-side and rotor-side freewheel component, providing defined accommodation for rolling members and axial engagement elements, which enhances stiffness, reduces weight, and improves assembly reproducibility by ensuring precise centering and increased axial support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a toothed disk freewheel is used to transmit driving force quickly, then the freewheel response speed is improved, but the bending moments cause the toothed disk to tilt which increases tooth wear and limits durability
Solution Approach 1:
The toothed disk is divided into two separate disks (first and second toothed disks) that can move relative to each other axially. This segmentation allows each disk to share the load and reduces bending moments on individual teeth, thereby reducing wear and improving durability while maintaining fast response speed.
Solution Approach 2:
The toothed disks are made dynamically movable axially relative to each other rather than being fixed. This dynamic configuration allows the disks to self-adjust and distribute loads more evenly during operation, reducing peak stresses and tooth wear while preserving the quick engagement capability.
2Device complexity
If axial forces are transmitted radially through bearings into the hub shell, then the hub structure is simplified, but the high loads may result in the hub shell breaking or require reinforcing which increases weight
Solution Approach 1:
The force transmission path is changed from radial to axial direction. The axial forces are transmitted through the axial movement of toothed disks rather than being converted to radial forces through bearings. This dimensional change eliminates the need for radial force transmission through the hub shell, avoiding the need for reinforcement and reducing weight.
3Ease of manufacture
If the hub-side freewheel component is screwed into the hub shell, then the assembly is simplified, but the radial tolerance varies depending on manufacturing tolerances which affects wheel centering precision
Solution Approach 1:
A centering portion with centering elements is introduced as an intermediary between the hub-side freewheel component and the hub shell. This centering mechanism mediates the connection by providing precise radial positioning independent of the screwed connection tolerances, thereby ensuring accurate wheel centering while maintaining assembly simplicity.
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
The design achieves a lightweight and stiff hub architecture with improved assembly reproducibility, reduced wheel centering errors, and increased durability by distributing loads more evenly, thus enhancing the overall performance and longevity of the hub.
Implementation Method 1
a hub shell which is rotatably supported relative to a hub axle by way of two roller bearings disposed on opposite end regions of the hub shell
Implementation Method 2
the rotor being rotatably supported relative to the hub axle by means of at least two rotor bearings
Data Source
AI summary
A hub for bicycles including a hub shell which is rotatably supported relative to a hub axle, a rotor rotatably supported relative to the hub axle by means of two rotor bearings, and a freewheel device having two interacting freewheel components namely, a hub-side freewheel component and a rotor-side freewheel component. The two freewheel components each include axial engagement elements and they are movable relative to one another in the axial direction between a freewheel position and an intermeshing engaging position. Rolling members are provided for defined accommodation in the hub-side freewheel component to support the hub shell relative to the hub axle. An attachment portion and a centering portion are configured in the hub shell and an attachment area and a centering area are configured on the hub-side freewheel component. The attachment area is connected with the attachment portion and the centering area is centered on the centering portion.