$700 wheel gives bicyclists a battery boost

The Copenhagen Wheel from startup Superpedestrian helps accelerate a cyclist going uphill, charging its battery with energy stored while braking and descending.

The Copenhagen Wheel from Superpedestrian gives a battery-powered assist to cyclists going uphill and recharges its battery when they're descending or braking.

(Credit: Superpedestrian/Michael D Spencer)
A Cambridge, Mass.-based startup is ready to bring some of the virtues of electric cars to the bicycle business.

On Tuesday, Superpedestrian began selling the Copenhagen Wheel, a rear wheel for a bicycle that converts the energy of braking and descending into a battery-powered boost when it's time to go uphill or to go faster along the flats. The first products are scheduled to ship at the end of the first quarter of 2014.

The 12-pound Copenhagen Wheel is available for $699 in a single-gear configuration, but it'll cost more for those who want to slip on a cassette with multiple gears. The first 1,000 of them are being hand-built now and will be available for mountain bike and road bike wheel sizes.
The lithium-ion battery recharges automatically when a rider descends a hill or rotates the bike's pedals a quarter turn. And it adjusts its operations automatically, the company said in a statement:

The Wheel is ridden like a normal bicycle -- users pedal and the motor phases in and out automatically. The Wheel learns about the rider and intuitively recognizes how hard he or she pedals and the topography ahead to determine how much support the rider may need. There aren't any additional throttles, wires, or buttons, maintaining the pure simplicity of cycling.

The Copenhagen Wheel is shown here on a bike with a single rear gear, but it's also available for multispeed bikes that change gears with a rear derailleur.

(Credit: Superpedestrian/Michael D Spencer)  

The technology also includes a mobile app that lets people adjust settings and monitor fitness statistics such as elevation gained and calories burned. In addition, the wheel can automatically lock itself when its owner leaves and unlock when its owner returns, the company said.
Adding a 12-pound weight may sound like a lot of extra burden for a cyclist. But its battery is enough for a 20-mph speed and 30-mile range, the company said.

In October, Superpedestrian announced it had raised $2.1 million in first-round funding from Spark Capital and David Karp, the founder of Tumblr.
Superpedestrian Chief Executive and co-founder Assaf Biderman also is an associate director of MIT's Senseable City Lab, where he and others developed the Copenhagen Wheel.