Hubless E-Bike

This project focuses on the design and theoretical validation of a hubless orbital wheel system for an e-bike assembly. Developed over 15 weeks, the research transformed a high-concept aesthetic vision into a functionally viable urban commuter that operates within a strict budget. By relocating the load path from a central axle to the wheel's outer periphery, the design achieves a lower center of gravity and direct force transmission.

Traditional bicycle wheels rely on tension-based load transfer through spokes. In contrast, hubless architectures create Structural Load Path Redundancy, shifting the burden to a bending-dominated rim structure. My research addressed three primary barriers:

Localized Stress: Managing 1200N vertical loads and 780N tangential stall-torques entirely through a peripheral interface.
Bearing Durability: Mitigating accelerated wear on the "long racetracks" of large-diameter bearings.
Economic Constraint: Reconciling high-performance requirements with local supply chain costs.

Niche Research: Stall Torque Analysis

While existing literature often focuses on static weight, this project establishes Stall Torque (780N) as the primary design constraint. This represents the "Worst-Case Scenario" launch where the motor attempts to move a 120 kg mass against 100% road grip.
Mathematical Justification: Engineered a 1:2.875 gear ratio for a 250W geared BLDC motor, resulting in an effective wheel torque of 143.5 Nm.
Efficiency: Targeting a 25–30 km/h cruise speed Keeping Drag to a Minimum, as well as allowing for a compact 1.2 kWh LFP battery.

The Geometric Evolution & CAD Modeling Workflow

The modeling phase was not merely about aesthetic replication but about defining a functional interface between stationary and rotating components.

Using ANSYS Workbench, I conducted a comparative material study across Aluminum 2024-T3 and Magnesium AZ31B on various models to verify whether my understanding of force application was correct based on other Reserch Papers Followed by iterative Process to correct error and try various aproaches to verify my model & research

The Control: Benchmarking Spoked Wheel Mechanics

Before engineering the hubless system, a baseline study was conducted on a traditional spoked wheel to map standard load paths. Using a 6-spoke control, we analyzed how 1200N of vertical load as well as Torque of 780 N is distributed through tension-balanced members to the central axle using various types of Configurations for analysis. This established a numerical benchmark for "Normal Stress" and deformation, allowing us to quantify exactly how much structural rigidity is traditionally lost—or gained—when the central hub is removed.

The Translation: Peripheral Force Mapping

The secondary phase involved "reversing" the traditional physics by applying forces directly to the rim border. In this stage, we replaced the central axle fixed-support with an internal stationary ring and applied the 780N Stall Torque tangentially to the outer rim. This iterative simulation step was critical to identify localized stress concentrations in the Magnesium and Aluminum alloys, ensuring that the bending-dominated rim could survive the "Worst-Case Scenario" launch without a central hub to dissipate the energy.

Hubless Bike Results

The Aluminum 2024-T3 rim demonstrated superior stiffness

System Specifications & Budget

The final "Budget-Spec" configuration ensures the vehicle is both thermally stable and economically accessible.

Total Project Cost: ₹49,000 (Target: ₹50,000).
Safety Factor: Exceptionally high, as the rim was stress-tested at 780N—far exceeding the 143.5N operational load.
Thermal Management: Cruise temperatures maintained at 45.88°C, well below the Class F (155°C) insulation limit.

Key Learnings & Skills

Constraint-Driven Design: Pivot from a 1500W "high-end" concept to a 250W feasible reality based on cost-benefit analysis.
Advanced FEA Integration: Applying complex boundary conditions, such as "Fixed Support" on inner stationary rings and tangential torque on rotating rims, to mirror physical reality.
Material Selection: Evaluating Young’s Modulus and yield strengths to solve specific mechanical failures like structural torsion and buckling.
Economic Feasibility: Sourcing local components to ensure the design is not just a prototype, but a scalable urban transport solution.

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