The Airless Bike Tires made by Britek was developed to eliminate the necessity of air in tires and to help the prevention of punctures, tube replacements, and pressure checks. The ‘Energy Return Wheel’ is a concept by Colorodo-based designer Brian Russell.

Instead of air, it uses rubber stretched over a series of carbon nano tube reinforced composite rods to provide its cushioning. These rods can be adjusted, changing the tension of the rubber to suit different types of terrain, improves flexing and recoil cycling. With the intention of reducing weight, a 29er wheel made from carbon fiber is incorporated. Further improvements include the possibilities of implementing a thin sidewall to keep mud and trail debris out for a more consistent ride.

Source: http://www.energyreturnwheel.com