A major problem for cyclists is how to prevent tires from going flat, but puncture-free wheels now under development by Bridgestone Corp. and Bridgestone Cycle Co. are expected to solve that problem once and for all.
The special tires, which do not use air, are being developed at Bridgestone's technology center in Kodaira, a city in the western Tokyo metropolitan area.
An Asahi Shimbun reporter visited the manufacturer to test the innovative product ahead of its release scheduled for 2019.
The wheels are made of high-strength, flexible thermoplastic resin that is covered in a layer of rubber.
Conventional tires attain a high level of resistance to shocks from the ground based on the impact absorption feature of rubber and the air in the inner tubes.
The new air-free wheels adopt specially designed, flexible spokes, so they can absorb shocks.
Each of the spokes is curved like the handle of a spoon when viewed from its side, and the thickness of the spoke’s outer part is slightly different from that of its inner part.
The unique design was devised after structure analysis had been conducted to improve the tires’ shock absorption feature, according to Bridgestone officials.
A trial ride of a bicycle fitted with the air-free wheels showed the tires were as comfortable as ordinary wheels when running on flat roads. However, the airless tires, when running on steps, absorbed the shock less than normal wheels.
Meanwhile, the air-free tires provided a more stable ride because the contact area between the tires and ground is larger to improve stability, the officials said.
Although the cross-section of conventional tires must be round as tubes are inside them, the airless wheels can be more freely designed.
The new tires are expected to meet the needs of customers who prefer stability to speed, according to Bridgestone.
During the trial ride, the spoonlike spokes were shining in the sunlight as the wheels were rotating. The stylish design of the new tires will appeal to young fashion-minded customers.
As the air-free wheels are currently estimated to be more expensive than ordinary tires, a challenge for the manufacturer is how it can lower the price.