I’ve long been a bicycle commuter. And with the rise of urban bike-share programs, many more people are finding the benefits of biking, both for individuals and cities. More bikes on the road means less car congestion and less pollution, and it’s a good way to get exercise.
But what if biking to work or school is just too far or hilly? That’s where Superpedestrian wants to come in. The MIT spin-out is commercializing the Copenhagen Wheel, a back bicycle wheel equipped with an electric motor. The wheel, which comes with a tire, is designed to replace an existing rear wheel and should fit most, but not all, bikes. It won’t do the work for you, but it will assist your pedaling and perhaps make that commute or workout less daunting and more enjoyable.
I took a bike with a prototype wheel for a ride to get a feel for the electric-assist. My spin near the company’s Cambridge offices was an eye-opening experience and lots of fun. I left thinking how this electric bike is really a smart bike and about the role sensor-packed bikes could play in cities in the future.
The company’s office looks like a typical startup, with desks filled with computers and engineers, except there’s a bike rack in the entry way and a work shop in back. The shop has the sorts of industrial tools need to make new hardware, including an industrial lathe and a 3D printer for quick prototyping.
The roots of the Copenhagen Wheel are in MIT’s Senseable City Lab, which developed the wheel for the 2009 United States Climate Conference at the request of city leaders. Even though prototypes have been around since then, only Superpedestrian, which raised $4 million in September, has a license to commercialize the technology.
Most electric bikes have battery packs that connect to an electric motor to turn the rear wheel. The Copenhagen Wheel has everything enclosed in a circular red hub that’s about half the diameter of a full wheel. The spokes connect to that inner wheel, rather than the bike’s original hub.
Inside the wheel is both the motor and batteries. What makes it a smart bike is the twelve sensors inside, such as an accelerometer—the type used on a smart phone—to sense when you’re biking up hill. That tells the motor to ramp up the power it delivers, lightening the load for the cyclist. Indeed, the core intellectual property at the company, which employs a number of robotics engineers, is the control system, which is designed to adjust power to the road and learn an individual’s pedaling style.
The bike comes with an app that, at this point, is fairly simple. It lets you chose among different modes—eco, standard, and turbo. You can also track your battery charge and miles. The company is working on an API and software development kit to let outside developers use the data from the bike in different ways, such as tying in bike workouts to fitness apps.
But once you start to aggregate the data, you can imagine how bikes become one more sensor on a city-wide network. Superpedestrian could learn common biking routes and give city planners valuable information, such as the location of potholes, using the hub’s accelerometer and smartphone GPS.
Moments after returning from my ride, engineers were able to pull up a small pile of data on it, which was remarkable. They showed me where I went on a map, the changes in speed, battery charge, and a long list of other technical data. Most of the log data is obscure but one could imagine apps that provided daily, weekly, or monthly recaps of your rides, or perhaps tell you where other Superpedestrian riders were.
Regen, baby
So what’s it like to ride? In a word, fun. With the electric assist, you only need a few pumps of the pedals to get to 20 miles per hour (the app has a speedometer; your smartphone mounts on the handlebar). That acceleration is a big advantage if you’re pulling out into traffic to take a left turn or need to pull around a bus stopping to pick up passengers.
But the designers of the Copenhagen Wheel aren’t trying to build an electric moped or scooter. In fact, getting above 20 miles per hour was difficult to sustain because the motor is limited at that speed for regulatory reasons. Beyond 20 mph, it becomes a different class of vehicle.
An intriguing aspect to the electric drive is the regenerative braking. Just like a hybrid car, the hub’s motor can recharge while slowing down or braking. (Essentially, the motor is running backwards and converting motion into electricity.) I think this will be a feature riders will quickly get used to and enjoy.
On the prototype I rode, I pedaled backwards to have the regenerative braking kick in. The regen was fairly powerful and it slowed me down substantially during my ten-minute ride, almost as if I was downshifting a manual transmission car. How this shows up in the final product is still being worked on, says Andrew Schmidt from Superpedestrian. The transition from biking full-on to coasting was a little choppy, but Schmidt says that, too, is something they’re still fine tuning.
As for cost, at $799 the Copenhagen Wheel is less than many electric bikes but more than most conversion kits. Its chief selling point is really the design: As an enclosed device, it’s simple to install and, as long as the wheel is locked, could be left on city streets. And having an accompanying app will be appealing to anyone who’s interested in tracking their movements and exercise.
It will come for fixed-gear and multiple-speed bikes. First shipments are expected at the end of the year. The replacement wheel weighs about 13 pounds, noticeably more than a regular wheel. The range will depend on the type of riding but the battery will need to be recharged about every 30 miles, Schmidt says.
Ultimately, what’s most compelling to me is that the Copenhagen Wheel could make the city smaller and biking accessible to more people. Instead of replacing the bicycle, it’s just making it smarter, starting with the rear wheel.
