Published 2014-05-06
The Indie Project is an e-bike concept based on sheet metal structures.
Legend for the exploded view:
- Side panels
- Seat height adjustment
- Electric hub motor
- Batteries
- Motor controller electronics
- Regular drivetrain
- LED housing
- Stiffener
- Power switch, gauges
- Stringer
- Regular fork and headset
- Reinforcement around highly loaded areas
Concept
What kind of bicycle project would a skilled hobbyist want to build? First, the instructions and CAD files should be available online for free. Second, the parts should be easily subcontracted from a local workshop and assembled without jigs and fixtures. Third, the design should be adaptable to personal requirements and taste thanks to a parametric design.
The Indie is an open source vehicle concept based on sheet metal. The design is freely distributed and can be modified by anyone familiar to CAD. The idea is to utilize sheet metal in a panel structure instead of a tradition truss construction using tubes. Main advantages are:
- Simplicity of the structure
- No initial investment in moulds and tooling
- Ease of manufacturing
- Assembly without jigs or special tools
- Low skill-level required
- Straightforward integration of batteries and electronics
- No heat input needed
- Large surface area for graphics, advertisements or even solar panels
The main drawback is added weight, but in the case of an e-bike with heavy batteries and motor the disadvantage is not significant. The required parts can be ordered from most modern sheet metal shops and assembled in one evening using a few cheap tools. The Indie concept proves that complex and multifunctional structures can be made with simple manufacturing methods.
Construction
The frame consists of 23 sheet metal parts that are joined using adhesive bonding. Blind rivets are used for alignment and pressure during bonding. The sheet metal parts can be cut using a 2D laser or water-jet cutter and folded using simple tools. Most of the bends are 90 degrees. The prototype frame is made from 1.5 mm aluminium alloy and it weighs 3,5 kg. Thinner material will result in weight savings. However, more complicated stiffeners are required in places where buckling is an issue. The structure would be more efficient if it were more of a shell type construction, but we wanted to keep it as an open sandwich/stiffened panel solution.
Acknowledgements: We wish to thank SBA Components, SolidWorks Corp, Novelis and 3M Finland for supporting this project and Simon Lessels for giving the inspiration for this concept.
The Indie bike won an award in the biennial Plootu Fennica sheet metal design contest.