When Tiller Rides began, we didn’t set out to build a new eBike around a revolutionary frame. In fact, we didn’t set out to build an electric bike at all. What we set out to do was build a bike that had all the features urban riders said they needed to make riding for everyday transport as easy as using a car.
What they wanted was a bike that could be used in everyday clothes without getting dirty or sweaty. They also wanted it to be easy to use and not require lots of accessories to be carried around. And finally they wanted it to be stylish so they could use it for all types of trips - including getting to and from work in work clothes, going out for dinner, or attending a work function.
To meet all these demands the Tiller Rides design team needed to create a bike that was stylish, had electric assist, and seamlessly integrated a wide range of needed features.
It was this last requirement, feature integration, that required us to rethink the standard tubular bike frame.
A 3D model of the Prototype 3 (P3) frame - 2019
The Tubular Bicycle Frame
In 1885, John Kemp Stanley invented the modern bicycle with a standard tubular frame. It was such a great invention that little has changed since then! While updates have been made to the frame to make it thinner, lighter, and more aerodynamic, its basic design remains the same.
While this is a sleek and practical design, its main drawback is that the tubes are generally small in diameter with little space inside. This means additional features such as lights and locks need to be bolted on from the outside. With the advent of the electric bicycle, the limitations of a tubular bike frame become more apparent: where do you put large items such as motor electronics, displays and batteries?
Artist's depiction of the first safety bicycle from the 1880s. Image courtesy of Pixabay.
The Dawn of a New Bicycle Frame Design
This got us thinking… How can we integrate all the modern features and accessories into one stylish frame? We couldn’t make micro-components to fit inside tiny tubes, so we needed to consider using a different frame. A frame that is hollow and could house most of the features internally without affecting the aesthetics. A new frame.
After careful consideration and extensive research, the Tiller Rides designers decided to use a monocoque-type frame. Monocoque means “single shell” in French and is a structural design where the load (weight) is supported by the external skin as opposed to the internal load-carrying frame - like an egg shell.
A monocoque frame design allowed us to reimagine bicycle design, opening up a world of possibility. We were no longer restricted to just bolting on accessories; by distributing the load across the external frame we could hide away all the electrical components. This allowed us to build in innovative design features - like an integrated cable lock and auto-start front and rear LED lights - without sacrificing on aesthetics.
Interestingly, the car industry made the shift from tubular (or chassis) frames to monocoque-like frames in the 1920’s and 30’s. While ultimately a pure monocoque frame was not the optimum solution for cars, most modern cars are still semi-monocoques and made of pressed sheet metal.
Despite the many potentials inherent in monocoque frames, and its early adoption in the car industry, there have been very few experiments with monocoque-type frames in the bicycle industry.
The Roadster's monocoque frame is the first (that we know of) used on a commercially produced bicycle. This innovative piece of engineering sets a new standard in eBike design and paves the way forward to a world where micromobility is accessible, functional, and stylish.
Prototype 3 (P3) at Kidogo Art House, Fremantle - 2019