A few years ago, I came across this scan from the January 1988 issue of “Cycle Sports,” a Japanese cycling magazine.  Within a longer article about 3Rensho aluminum road bikes is a feature on a prototype carbon frame called the “Carbo-Panel.”  Designed by 3Rensho and manufactured in partnership with Nikko Sangyo and Shimano, it featured a unique design consisting of two carbon panels (2-5mm thick) that form the frame of the bike.

At the time this was written, most of the carbon frames on the market used tubes that were chemically bonded together.  The Carbo-Panel no underlying frame structure and is hollow inside, with the panels functioning as the frame.

Components like the fork and seat post are mounted directly to these panels.  The article notes that the frame can be adapted to fit riders of different sizes based on where the components are mounted.

The article goes on to point out that this is a prototype, complaining that “rigidity in the vertical direction is too strong,” and suggesting that it could be improved by adding a cut out to the central part of the panel.  Around the same time this article was published, the prototype was being displayed at the 1988 World Cycle Fair in Long Beach, California. The author goes on to say they look forward to a test ride, which will be written about in the February issue.  I don’t have a copy of that review, but in April 1988, a complete Carbo-Panel made the cover of the Japanese cycling magazine “New Cycling“:

Google translated from the original Japanese, the Editor’s note states:

“It is self-evident that when an object’s material changes, it naturally has certain material properties, and its shape changes accordingly.  Bicycles, which have entered an era of new materials, are no exception.  I just so happens that in this day and age, new materials are being handled, discussed, and made within the expanding field of steel production.  In the future, if bicycles made from new materials, including their parts, are conceived and made in a completely different dimension from steel, they will undoubtably be called “new material bicycles” in both name and reality.”

I hope to find more about this carbon prototype in the future, including any ride reviews, if they exist.  In the process of researching this bike, I came across a collaboration between pioneering American carbon bike designer Brent Trimble and Zunow.  My next article will be all about it.