Here’s a little more on the history behind aerodynamic bicycle frames; a subject that I touched on in my previous blog about the US team bikes.
In the mid 1970s there was a craze for drilling holes in components to save weight. Soon no component part of the bicycle was left untouched, with the possible exception of handlebars and stems for obvious reasons; although a few riders with death wish tendencies even tried that.
Steel frames were not immune, with cutouts in the bottom bracket shell and lugs. Towards the end of the 1970s I saw a few British Time Trial Frames with slots cut in the head tube, and matching slots in the steering column inside.
Soon bikes had so many holes in them, they didn’t have a shadow.
Aside from reducing the reliability of the frame or component, people began to point out that any gain in weight saving was offset by the increased air turbulence and the resulting drag of air passing through slots and holes.
People began to think seriously about aerodynamics. At the same time the East Germans were experimenting with aero bikes and helmets; I was one of the first in England to work with the idea in the late 1970s. I made a press tool to form round tubes into an oval shape. I also added an aerofoil behind the head tube and bottom bracket shell.
After the US team bike fiasco I lost interest but I do remember building one at the end of 1980. I had just started work for Masi in Southern California, and they had a sample set of aero tubes. (Japanese I believe.)
I built one Aero Masi frame for the New York Show in February 1981. It was built into a complete bike, light blue in color, and with all the Masi decals it was a very unique and classy looking machine. I wonder where that one is now; definitely one of a kind.
The aero steel frame never really caught on and was only around for about two or three years. The tubes were difficult and therefore expensive to produce. The frame had to be of a lug-less construction, not conducive to mass production. The biggest drawback was the extra weight because the tubes had to be straight gauge. They couldn’t be double butted like round tubes.
Footnote: The pictures are of an English built track pursuit frame built around 1978. Note the extended seat tube, round at the top to accept the seat post. The fork crown was a modified Ron Kitching crown that took the old style narrow Reynolds fork blades, and was hand filed into the aero shape. Also, see details of the aerofoil behind the BB and head tube.