Re: [CR]Re: Frame Fatigue


Example: Events:Cirque du Cyclisme:2007

From: "stevens" <stevens@veloworks.com>
To: tsaleh@rocketmail.com, BobHoveyGa@aol.com, classicrendezvous@bikelist.org
Subject: Re: [CR]Re: Frame Fatigue
Date: Tue, 10 Jun 2003 09:34:50 -0700
In-Reply-To: <20030610151415.32356.qmail@web41102.mail.yahoo.com>
References: <144.1345ddde.2c1748ae@aol.com>


Personally, I'm experiencing a little "cyclic softening" myself; especially around the middle ... but I think that has more to do with NOT riding the bikes.

Steven L. Sheffield stevens at veloworks dot com veloworks at worldnet dot ay tea tee dot net bellum pax est libertas servitus est ignoratio vis est ess ay ell tea ell ay kay ee sea aye tee why you ti ay aitch aitch tee tea pea colon [for word] slash [four ward] slash double-you double-yew double-ewe dot veloworks dot com [four word] slash


---------- Original Message -----------
From: tarik saleh
To: BobHoveyGa@aol.com, classicrendezvous@bikelist.org
Sent: Tue, 10 Jun 2003 08:14:15 -0700 (PDT)
Subject: Re: [CR]Re: Frame Fatigue


> Jan writes:

\r?\n> > (I am sure

\r?\n> > >somebody will explain that frames get soft with use

\r?\n> > and "reset" after

\r?\n> > >a rest.)

\r?\n>

\r?\n> BobHoveyGa@aol.com wrote:

\r?\n> > Bicycles are the same way...

\r?\n> > after a ride, they must have a rest period for the

\r?\n> > frames to "reset".

\r?\n> > Therefore it is essential for any serious rider to

\r?\n> > have a stable of bikes to prevent

\r?\n> > "frame fatigue"... at least that is what I have told

\r?\n> > my wife.

\r?\n>

\r?\n> Interestingly, cyclic softening and hardening are real

\r?\n> phenomena, as is strain rate sensitivity.

\r?\n>

\r?\n> Cyclic softening is when, with (for example) a

\r?\n> constant load, each fatigue cycle results in more

\r?\n> deflection. Cyclic hardening is the opposite. I am

\r?\n> pretty sure the reason I get beat in sprints is that

\r?\n> my bike is exhibiting cyclic softening, while my

\r?\n> competitors is just the opposite allowing him or her

\r?\n> to beat me by ensuring more of their power goes to

\r?\n> beating me and less to making their bike softer with

\r?\n> age. Damn them.

\r?\n>

\r?\n> Additionally, I think strain rate sensitivity would be

\r?\n> a good description, if very loosely and inaccurately

\r?\n> applied, to the interesting observations of Jan and

\r?\n> Bob above. Correctly, one sees strain rate

\r?\n> sensitivity when puling a piece of silly putty. Pull

\r?\n> it real slow and it exhibits super plastic behavior,

\r?\n> extending many times its original length before it

\r?\n> breaks. Pull it quickly and it snaps at very small

\r?\n> strain.

\r?\n>

\r?\n> Quasi-tangentially, I think the idea of given frames a

\r?\n> rest between rides can be loosely described as letting

\r?\n> the fatigue damage anneal itself out with time (as the

\r?\n> atoms migrate about) at room temp. Aluminum is even

\r?\n> better for this as many alloys will undergo room temp

\r?\n> aging phenomena, but of course this is OT.

\r?\n>

\r?\n> So, in conclusion, when asked "why I need so many

\r?\n> bicyles " I will tell people the following:

\r?\n>

\r?\n> Due to concerns about cyclic softening and strain rate

\r?\n> sensitivity, I need to age my bikes, reversing fatigue

\r?\n> damage, so I rotate each bike in and out of service to

\r?\n> ensure that each bike is at its very freshest each

\r?\n> time I ride, anything else would be uncivilized.

\r?\n>

\r?\n> (phenomena are real, application of said phenomena was

\r?\n> done EXCEPTIONALLY poorly for humorous effects)

\r?\n>

\r?\n> Tarik, materials magician

\r?\n>

\r?\n> =====

\r?\n> Tarik Saleh

\r?\n> PO box 1326, Knoxville, TN 37901

\r?\n> tsaleh at rocketmail dot com

\r?\n> Bicycles, bicycles, bicycles:

\r?\n> http://www.engr.utk.edu/~tsaleh/bike.html