Re: [CR] ...now: frame geometry

(Example: Framebuilders:Chris Pauley)

From: <Stronglight49@aol.com>
Date: Sun, 20 May 2007 18:32:45 EDT
Subject: Re: [CR] ...now: frame geometry
To: classicrendezvous@bikelist.org
cc: OROBOYZ@aol.com

Welcome, Dave.

I think Dale has a good point. Without meaning to suggest there are Mystical properties to vintage bikes, perhaps there really are somehow undefinable differences. I know I have struggled to discern the differences between my own, and have come up with just contradictions in how some bikes "should" handle and how others actually do ride. I'd certainly welcome any solutions to the puzzle.

I always struggle to make ALL of my own (vintage) bikes conform to my own basic size requirements by raising or lowering the saddle or stem heights, the fore and aft movement of a saddle and the extension length of the stem and drop of the bars. This was never a scientific effort on my part but rather just wanting a comfortable riding position in the imperfect world of NON-custom framesets. I did observe that after experimenting individually with many different bikes, there were certain consistencies in, for example, the distance of the saddle to the top of the bars, or with different style levers (such as vintage Campy versus STI) all of my optimal positioning for each bike had fallen within perhaps 1/4 to 1/2 inch of each other - regardless of tubing angles. Yet, the rides of each bike, regardless of minimizing the differences of sizing as much as possible, was quite different. In fact, in my experience, even bikes of the same dimensions, same frame size, same saddle and components, and even (intentionally) set up with the same tires at the same pressure can have a very different "Feel". Don't ask me why; I just accept this as one of those Mysteries I will never understand. There surely must be a way to catalogue and define all the differences in order to re-achieve one's subjective "perfect" bike... and yet?

I recall Brian Baylis this Fall had commented about having had a bike built for him by another builder. It was deliberately designed with exactly the same proportions that he had found perfect on his Masi, so he assumed it would also have this same perfect handling and ride characteristics as on the existing bike. But, it turned out to be a terrible disappointment. The construction was certainly excellent, and yet it somehow turned out totally different when he had attempted to simply clone his bike.

I recall also reading an article a few years back in a popular cycling magazine. The author's point was to de-mystify the often "claimed" differences between the ride of a steel, aluminum, carbon or titanium bike. He carefully masked each bike with foam padding or some such to disguise each of the bikes so there would be no assumed differences impacting the results of the tests. Even the same tires were used. The outcome was that several serious, semi-professional caliber, riders all came up with different guesses about each of the bikes they rode... and none were exactly correct. I think the problem with this test was that all the bikes were modern. Although there were differences in materials and costs, they were all essentially racing (or pseudo-racing) bikes and therefore, regardless of the manufacturer, they all had basically the same geometry and were intended to maintain the current standards of stiff non-flexing construction considered a desirable attribute for a racing bike. If you are intending to level out all the variables, with modern materials and construction techniques this seems easily done... and (just my opinion) all modern bikes do seem pretty much the same beyond the cost and cosmetics.

I think with vintage road bikes, from the 30s to 80s, there were/are almost infinite subtle differences... the reason we all like them so much. And also why we admire the modern custom hand builders as well.

Interesting subject, indeed.

Bob (19 bikes and holding) Hanson, Albuquerque, NM, USA

Welcome Dan, you sound like you are a super addition to our strange assembly of cycling aficionados!

The frame geometry web site shown on your e-mail signature interested me..

http://home.comcast.net/~pinnah/dirtbag-bikes/geometry-project.html

Pretty much fun trying to catalog and categorize that information!

My first thoughts were how bikes with almost-the-same geometry (assuming "identical" is impossible) often "seem" to ride differently... The whole process of "ride" is so subjective and not able to be measured. Lordy, many have tried and tried to evaluate "ride" but it is still an elusive art...

The other thought that might be fun to hear others discuss is that of chain stay length, or rather, how one measures that dimension on horizontal drop out bike frames (road, not addressing track dropouts) ...

You suggest measuring to the linear extensions of the seat & chain stays/ Other approachs: - The mathmatical mid point in the drop out slot. - The center of the derailleur hanger (McLean Fonvielle used this method.) - The spot where the rear axle might most logically be positioned (hard to say sometimes!)

Are there other approaches?

Dale Brown Greensboro, North Carolina USA

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