Re: [CR] Frame stiffness NOW Frames Getting Soft and 753


Example: Racing:Wayne Stetina

In-Reply-To: <20100706220617.A776219D8D@ug6.ece.ubc.ca>
References: <20100706220617.A776219D8D@ug6.ece.ubc.ca>
Date: Tue, 6 Jul 2010 16:10:58 -0700
From: Jim Merz <jameshmerz@gmail.com>
To: donald gillies <gillies@ece.ubc.ca>
Cc: classicrendezvous@bikelist.org
Subject: Re: [CR] Frame stiffness NOW Frames Getting Soft and 753


What you seem to be implying is that the tubes get hot from flex. A carefully designed spring is very efficient and will not generate very much heat in use, this is especially so in the case of a bike frame. While it is true on some really small scale that springs generate heat in use let's look at another high tensile steel part designed for flex, a valve spring for an internal combustion engine. In the case of very high RPM racing engines the stress on this spring is amazing. With proper material and manufacture these parts almost never fail, or will fail after a known number of hours use so can be changed out before this happens. They fail from fatigue, not from sag. When was the last time you had to change the springs in your car?

Jim Merz Big Sur CA

On Tue, Jul 6, 2010 at 3:06 PM, donald gillies <gillies@ece.ubc.ca> wrote:
> Ok, please stop those cards and letters with my :-) posting. I got my
> head handed to me because I incorrectly stated that heat-treating
> increases tubing stiffness (the stiffness of all steels is roughly
> constant.)
>
> I do think it's possible, though, over the long term, for a reynolds
> 753 frame, with thermal input at room temperature, to loses some of
> its heat-treated properties, that was the main point of my message.
>
> - Don Gillies
> San Diego, cA, USA