MONODZUKURI

Air Supply

As bicycles are used, the air in the tires deflates naturally. This is why pumping up the tires from time to time is something that we all take for granted. But now Nakano Iron Works has developed a new technology which turns that common sense on its head. Miho Yanagisawa talks to Ryuji Nakano, the president of Nakano Iron Works, about the Air Hub and his faith in the concept of monodzukuri craftsmanship.

Bicycle manufacturing in Japan peaked in the early 1990s. At that time, eight million bicycles were produced in Japan, eight times the current level.

Back then, about half of all the hubs (the central part of the wheel) for the bicycles made in Japan were produced by Nakano Iron Works, a small company that was founded in Sakai City in Osaka Prefecture in 1948.

However, in the latter half of the 1990s, the market was swamped by cheap Chinese-made bicycles, and Japanese bicycle makers started to decline. As a consequence, Japanese hub makers also started to disappear one by one, and Nakano Iron Works was pushed to the point where it looked like it would only be a matter of time before they would have to close down.

“There was no way that we could keep up with Chinese made hubs in terms of price. I kept trying to think of some way to make a hub with high added value,” said Ryuji Nakano, the second generation president of Nakano Iron Works.


One day, he was talking to a bicycle manufacturer that was one of his clients. He asked about the kinds of things that bicycle users find inconvenient or unsatisfactory on a day-to-day basis, and was told that the number one complaint was rust, followed by theft and then punctures.

There was no obvious connection between hubs and any of these problems, but as the conversation went on, he learned that the most common cause of punctures is low air pressure in the inner tube. The surface of the inner tube inside the rubber tires has countless tiny holes that are invisible to the naked eye, so that a certain percentage of air leaks from these holes even if the bicycle is not ridden. As the pressure in the inner tube drops, it becomes unable to absorb shocks from the road surface as the bicycle travels along, which makes it more likely that the rim of the wheel will damage the tube, eventually resulting in a puncture. Accord­ing to the rubber manufacturers, it is impossible to completely eliminate the small holes in the inner tubes.

“In that case, it would be good if the hub could supply an amount of air equal to the amount that leaks out.”

President Nakano had a flash of inspiration. He could create a mechanism within the hub that can convert the rotational motion of the spinning wheel into a pumping motion, so that air can be sucked into the hub and compressed using pistons. The compressed air could then be supplied to the tube, with any excess air being released via a safety valve to keep the tube at the right pressure. This idea resulted in a revolutionary new type of hub. They encountered a vexing problem in the process of commercialization, namely that rainwater ended up becoming sucked into the safety valve, but after much trial and error, this problem was eventually solved with a dual-valve structure. The Air Hub was finally perfected a little more than two years after they started development work in December 2001.


The new product was a record-breaking hit, reaching its initial sales target of 10,000 units per year in just one month, and sales have grown steadily since then. Now, the Air Hub is available as part of children’s bicycles and wheelchairs, as well as normal bicycles, electric­-assist bicycles and bicycles with three-speed gears. And there is no need to buy a new model that comes with an air hub; Air Hubs can also be attached to existing bicycles by purchasing a wheel with a built-in Air Hub, or just the Air Hub on its own.

“Everyone thought that bicycles had already been perfected in their current form, and that there was no scope for making improvements. But only about a hundred years have passed since bicycles settled into their current form. There is no way that every possible development could have been made in such a short time. I think that there’s still a lot of room for improvement when it comes to thinking about safety and comfort. Like warm handle-bars for cold weather, for example,” Nakano laughs.

Following the dramatic decline of the bicycle industry, there was a brief time when Nakano even flirted with the idea of shifting to manufacturing automobile components. But it has been his strong belief that “I owe my life to my work in bicycle manufacturing” that has brought him this far.

“Where there is a will, there is a way.” With this conviction, Nakano Iron Works will continue to engage in monodzukuri.

Company name:	Nakano Iron Works
Established:	1954
President:	Ryuji Nakano
Head office address:	8-1 Tajii, Mihara Ward, Sakai City, Osaka Prefecture, 587-0012, Japan
Website:	http://www.nakano-iw.co.jp/index.html (Japanese only)

Miho Yanagisawa is a freelance writer.