The Copenhagen Wheel turns any bicycle into an electric hybrid
The heyday for electric vehicles was way back in the early ’30s — the 1830s that is. By 1867, a workable two-wheeled electric cycle was on display at the Paris World Exposition courtesy of Austrian inventor Franz Kravogl. In the early 1900s, the premier bike shops of the day, namely that belonging to the Wright brothers, were already building air-worthy contraptions. While Miss Gulch’s tornado-powered flying bike from The Wizard of Oz somehow failed to materialize for us, our consolation prize — an electric hub-motor plug-in for our smartphones known as the Copenhagen Wheel — is finally here.
The device is a swap-in style package that replaces your standard issue bike wheel with 350 watts of hill-busting, regenerative power-harvesting awesomeness. Not since the invention of the electric toothbrush has there been such smooth integration of manual and machine power available to us. The beauty of the design is that all the hardware — motor, control, and batteries — are squeezed into a pancake that still manages to fit between the back forks of a traditional bike. Therein lies the magic. Once you plug the enhanced bike into your phone it becomes your new bionic best friend, intuitively sensing how fast you want to go from the effort applied to your pedals much like the Segway responds to your lean.
What has made the electric bike motor such a unique challenge over the years is that while the demands for light weight in a slim footprint naturally suggest a motor-in-hub power design, getting enough low-RPM torque to the wheel without sophisticated and massive planetary gearing has always been problematic.
Flat motor designs (actually called pancake motors) have been around for a while, but have never been all that great as far as performance. Precision control of three-phase DC brushless motors, as exquisitely used in the Copenhagen Wheel, has now been perfected to such an art form that near-impossible wizardry Tesla himself could have barely imagined is now available for everything from simple computer fans to electric tanks.
- Motor: 350W, EU: 250W
- Size: 26 inches or 700c rim
- Battery: 48V lithium
- Connectivity: Bluetooth 4.0
- Range: Up to 31 miles (50 km)
- Battery life: 1000 cycles
- Charge time: 4 hours
- Smartphone OS: iOS, Android
- Compatibility: Single speed or 7/8/9/10 speed-free hub
- Top speed US: 20 mph, EU: 25 km/h
- Brake type: Rim brake and regenerative braking (downhill and back pedal)
- Weight: 13 pounds (5.9 kg)
- Dropout: 120mm (single speed, 135mm (single and multi-speed)
From the technical specifications above, we can see that while the Copenhagen Wheel is no beast, it does have an impressive array of features. Not least among them is a forthcoming SDK that hopefully will allow some customization. Once hackers can put a slave wheel on the front forks so that total power is more in the single horsepower range, then who knows, maybe even Americans will buy a few. Instead of the tandem concept, mount the two wheels in parallel, then suddenly a ZRT (zero radius turn) wheelchair design becomes interesting. With a little more imagination, spin a re-geared hub 90 degrees and stick a small prop on the end, and human-powered flight designs may get a much needed enhancement.
The main hurdle to widespread adoption of this kind of device is probably not technical, but rather legal. Every jurisdiction likely has its own interpretation of what constitutes license-worthy motive power. At a price point of less than $1000, many will hopefully be ready to find out for themselves what the Copenhagen Wheel will make possible.
Author: By John Hewitt