Re: [CR]30's Bike Geometries

Date: Fri, 15 Jun 2007 14:35:06 -0700 (PDT)
From: Jerome & Elizabeth Moos <>
Subject: Re: [CR]30's Bike Geometries
To: Jan Heine <>, Mitchell Gass <>,
In-Reply-To: <a0623090dc298471b6296@[]>

Were Pre-War bikes really super-long trail? If I understand the concept correctly, shallow head angles does increase trail. But doesn't a long fork rake decrease trail? Pre-war bikes typically had long fork rake as well. So was the net result really that drastically different from modern bikes with steeper head angle, but also less fork rake?


Jerry Moos Big Spring, TX

Jan Heine <> wrote: At 10:37 PM -0700 6/14/07, Mitchell Gass wrote:
>It's striking how different the geometries of 1930's road bikes like
>the Legnano currently on eBay
>are from modern bicycles. What was gained - and what was lost - in the change?
>Mitchell Gass
>Berkeley, CA USA

It is interesting how quickly bike geometries evolved in the late 1930s. By 1939, many bikes had geometries that were very similar to modern bikes. The sloping top tubes also went out of fashion, and most makers preferred level top tubes. I wonder why they did the sloping top tubes, because most racers had their handlebars much higher than those on that Legnano. Also, I suspect the Legnano was designed for much wider tires... look at those clearances!

Even after the war, when roads were much worse than before in many parts of Europe, builders did not go back to the super-slack head angles and super-long trail. From my experience riding bikes like the Legnano, they just don't handle as well as later machines. So I think there was some real progress, where builders finally did figure out the front-end geometry.

After the war, things were refined further, usually by steepening the head angle a bit more, until 73 degrees or thereabouts became standard.

Coincidentally, handlebar widths decreased tremendously as geometries changed. In the 1920s, it was common to have 50 or more cm wide handlebars. On those geometries, the added leverage probably is useful to fight the wheel flop. By 1939, handlebars rarely were even 40 cm wide, because you did not need to wrestle with the bike any longer. Of course, during the same time, the material of the bars changed in many cases from steel to aluminum, so one could argue that is was a fear of breakage that made manufacturers weary of extra-wide bars. But even steel bars became narrower. (Or was it that because of the war and malnutrition, riders' shoulder widths decreased?)

The 1930s altogether were a time of great change in racing bike design. This is a simplification, but effectively, a 1929 bike is closer to a 1900 bike than it is to a 1939 bike. And a 1939 bike is closer to a 1985 bike than to a 1929 bike. Whether you look at geometries, weight, materials... it all changed in the early 1930s.

I once rode a 1939 Oscar Egg that was very light (I recall 21 lbs.) and spirited. I wouldn't mind racing that bike today on a flat or moderately hilly course. The Super Champion changer worked well, but the gear range was rather limited... -- Jan Heine Editor Bicycle Quarterly 140 Lakeside Ave #C Seattle WA 98122