At 11:00 AM -0500 1/20/11, Harry Travis wrote:
>When I first read this, I though Jan had committed the reversal-of-intent
>too common to my efforts.
>
> (The geometry, with its super-long chainstays, is pure racing bike, though,
>rather than the shorter chainstays you found on French cyclotouring bikes of
>the time - funny how things changed, 20 years later, it was the racing bikes
>that had shorter rear triangles than the cyclotouring bikes!)
>
>Is an explanation for these in the pages of subscription BQ, or can you and
>others advance them.
I can't go into the same detail as the BQ article (nor can I reproduce the lovely Rebour drawings here), but in a nutshell:
The super-long chainstays of 1940s and 1950s racing bikes were
intended to provide a straight chainline. (Source: Jack Taylor,
interview in Bicycle Quarterly Vol. 7, No. 4. There are many other
references to keeping the chainline straight in the literature of the
time.)
>But, short chain-stays for cyclotourists?
Relatively short. In fact, by today's racing standards, they were still long. A good cyclotouring bike in the 1940s or 1950s had chainstays somewhere between 430 and 445 mm.
Basically, the design of cyclotouring bikes has changed little since 1945. Today's best constructeur bikes use geometries that are very similar to those used back then.
The article in Bicycle Quarterly Vol. 4, No. 3 examined different "trends" in racing bicycle design. These "trends" make it easier to understand why racers preferred cottered steel cranks over lighter aluminum cranks, or why Campagnolo C-Record was heavier than the Super Record it replaced.
At any given time, racers worried first and foremost about one aspect of cycle technology. Back in the 1930s and 1940s, it was mechanical resistance. Racers believed that a straight chain offered the least mechanical resistance. That is why Tullio Campagnolo offered his Cambio Corsa, which did not make the chain go around a figure-8 like touring derailleurs did. Adjustable chain tension was popular - racers believed that tensioning the chain increased resistance as well.
By the 1970s, light weight was the primary concern. Hence we see components like Campagnolo Super Record with titanium parts. By the mid-1980s, aerodynamics had replaced concerns over weight, so you get aerodynamic rear derailleurs and so on.
One thing has not changed at least since the 1930s: Racer ride hand-made tires, no matter what their sponsor's logos say. For good reason, because in a peloton, tire resistance appears to be the most important resistance of all. (Wind resistance is more important when you are riding alone, without a draft from riders ahead of you or a push from riders behind you if you are at the front of a peloton.)
Jan Heine Editor Bicycle Quarterly 2116 Western Ave. Seattle WA 98121 http://www.bikequarterly.com
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