The Evolution of Frame Design, Part II: How Economics Changed Design
Posted Oct 08 2009 10:00pm
In the 1960s the bicycle business in Europe went through a huge slump, at a time when the general economy boomed. In fact it was because of this boom that bicycle sales suffered.
Up until that period the bicycle was the way the working man got to work each day. In the early 1950s, I remember the factory where I worked as an engineering apprentice did not allow cars onto the premises, with the exception of a few top executives.
The factory, part of which was 100 years old, had no provision for the workers to park their cars. However, there were few workers who owned cars, those who did parked on the surrounding streets.
But I do remember there were vast areas of covered bicycle racks inside the factory gates, with provision for hundreds of bikes. Workers arrived each day on foot, by public transport, or mostly by bicycle.
In the 1960s as the economy boomed working people all over Europe started owning cars for the first time.
The adverse effect this had on the bicycle industry trickled all the way down to the lightweight racing bicycle. After all, bicycle racing was traditionally a working class sport.
Lightweight racing frames had always been supplied by small to mid size framebuilders.
In the 1960s many small builders disappeared, and the midsized companies struggled to keep going. They had to look for ways to increase production with fewer workers, and cut costs.
Up until the 1960s, frames were assembled one at a time, or in very small batches. No jigs were used; frames were assembled, angles measured, and the frame set on a crude template to check geometry. Often the template was nothing more than marks on a brick floor, and alignment was by the trained eye of the framebuilder.
I mentioned in the last article, the standard racing frame angles were 71 seat and 73 head angle. In the 1960s the 72 degree parallel frame became the standard. By making the seat and head tube parallel, the builder could make a smaller or larger frame simply by raising or lowering the top tube.
Simple fixed assembly jigs could be made, and top tubes were usually 22 ½ inches long, over a large range of sizes, making tubes the same size that could be pre cut. Hardly ideal for all riders, but they had to make do with a different length handlebar stem.
(Above.) The Viking Severn Valley frame is typical of the 1960s. The spec sheet that can be viewed here, lists the angles as 72 degrees parallel. 22 ½ inch (67cm.) top tube for all sizes from 22” to 25” (56 to 64cm.) The fork rake was 2 ½ inches (6.3cm.)
The reason 72 parallel was chosen first was because riders had been used to 71 degrees for such a long time, a 73 degree seat angle would have been a hard sell. However, by the end of the 1960s, the 73 degree parallel frame had become standard, and head angles were once again back to the ideal 73 degrees.
Another way costs were cut was by the introduction of pressed steel lugs. The old cast steel lugs, were expensive, crude, and took hours of hand filing to make them useable. The pressed steel lug is stamped from sheet steel, formed to shape and welded at the join. Lightweight, and uniform thickness, these lugs required only a minimum of work before assembling a frame.
Yet another way costs were cut in the late 1960s, was by dispensing with braze-ons, saving a tremendous amount of time and labor.
Customers were told that braze-ons weakened the frame, manufacturers who made brakes and derailleur gears supplied clamp on fittings.
Pictured on the right: A 1968 Italian Pogliaghi with everything clamp on, even derailleur cable guides.
During the 1960s it was economics that determined frame design. In Part III of this series, I will move on to the 1970s after the bicycle slump was over