History: Schwinn's Notebook on Post-War Rims

 Inventors and companies often turn to making detailed notebooks as a way of supporting a patent application and developing marketing strategies for new inventions. Bicycle inventors and companies are no exception to that. 

In this case, let's look at Frank W. Schwinn's notebook, made during World War II, in preparation for bicycle wheel rims after the war. This notebook section dates to 1945.

Page 1 of the notebook gives an overview of the various "Schwinn tubular" rims. These rims are called "tubular" not because they take sew-up or tubular tires, but because the metal that makes the rim starts as a tube and is stamped into the rim shape. Thus, the rim is two layers thick because the tube shape is pressed into the rim profile. The length of metal is cut, bend into a circle, and welded together end-to-end. These rims replaced the older Lobdell and similar rims from before the war. 

 

 

 Page 2 gives us a description of the sketches. The consumer spiel talks about strength and improvement over pre-war designs. The trade spiel talks about Schwinn's history of innovation and how these new rims would fit in. Many pre-war rims were single-layer, and those used on lightweight three speed bikes were often quite "slinky" and prone to going out of true. The Schwinn tubular rims were heavy, but also quite durable.

Page 3 of the notebook expands further on the trade spiel. How these new rims will improve bicycle wheels is described in some detail. The subject of weight is also introduced, as well as the resistance of the rims to elongation. 

Page 4 expands even more on the trade spiel and references improved profitability. Perhaps trade professional would have been more skeptical of new rims than consumers. I can understand that. How is Schwinn's rim better than any of the basic, pre-war types? Schwinn would have had to answer that question, which undoubtedly some trade professionals would have asked. 

Page 5 gives us some rudimentary cross-sections of the rim. This shows us that the tubular rim was hollow, whereas many pre-war types were single-layer with hooks for the tire beads.

Page 6 gives us some dimensions, including for lightweight bikes. Interestingly, Schwinn does not reference a proprietary "S6" size for the bead. Instead, he references use of the existing English sporting size of 26 x 1-1/4. (Today known as 597mm).