My "testing" was straight forward: built a rear tri with radically bent Columbus MAX ovalized seatstays (in a conventional S-bend pattern, not the plane Kirk uses nor taken to his extreme), and Columbus Foco seattube and chainstays all connected to a Paragon BB shell. I anchored the BB shell and seattube, placed a dummy axle in the dropouts and applied an estimated 300-lb load (I used a Parker pneumatic cylinder with a known cylinder surface area and a regulator of indeterminate accuracy so that 300-lb load is, again, an estimate). I saw repeatable movement on the order of .070" whereas on my personal bike with straight 19mm FOCO seat stays, I saw no significant movement, i.e., <.01". If you really want to bake your noodle, try the same test without seatstays. I found a 300-pound load without seastays will permanently alter the chainstays position relative to the BB, not by bending the stays themselves, but by distorting the BB shell.
What Kirk's testing method was I have no idea, I only know what I've read of his comments, and I've never discussed it with him. As far as the data being kept secret, what makes you think it's intentional or a conspiracy? I wouldn't "publish" my "data" at any level more formal than to describe it as I've done here: I neither promoted nor subscribed to a testing standard.
As a framebuilder, I've discovered all sorts of things about bicycles that the cognoscenti (I used that word for you, Richard!!!) claim to be untrue. My life is just one big X-File....
Cheers! Don Ferris Anvil Bikeworks, Inc. Littleton, Colorado Ph: 303.471.7533 / 303.919.9073 Fax: 413.556.6825 http://www.anvilbikes.com
-----Original Message----- From: classicrendezvous-bounces@bikelist.org [mailto:classicrendezvous-bounces@bikelist.org] On Behalf Of Todd Kuzma Sent: Thursday, July 01, 2004 10:43 AM To: classicrendezvous@bikelist.org Subject: Re: [CR]was The Modern Hetchins?, now seatstay design
on 7/1/04 10:47 AM, Anvil Bikeworks at ojv@earthlink.net wrote:
> If I recall correctly, he
> commented that its movement is in the 2-3mm range (around 1/8") which I
find
> completely believable and in accordance with my own "testing" of radically
> bent seatstays.
How was this figure determined? What type of load is necessary to get 2-3 mm of movement? What type of testing did you do?
So, if I understand correctly, there are data to support these claims, but for some unknown reason, the data are being kept secret? Pretty odd, don't you say?
Todd Kuzma
Heron Bicycles
Tullio's Big Dog Cyclery
LaSalle, IL 815-223-1776
http://www.heronbicycles.com
http://www.tullios.com