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


Example: Production Builders

From: Tom Harriman <transition202@hotmail.com>
To: <jameshmerz@gmail.com>, <gillies@ece.ubc.ca>
Date: Wed, 7 Jul 2010 00:31:39 +0000
In-Reply-To: <AANLkTinxeGPsPoz2H0pRlsnZIyoHRQP6MNZrwB2VsI5H@mail.gmail.com>
References: <20100706193407.36BE819D8D@ug6.ece.ubc.ca>
Cc: Classic Rendezvous <classicrendezvous@bikelist.org>
Subject: Re: [CR] Frame stiffness NOW Frames Getting Soft and 753


Hi Don.

In my experiences with Reynolds 753 non of these things has ever happened to me. In 1999 I had Steve Rex build me a frame and fork from 753, and eleven years later the bike is still a joy to ride. I know this is only one example, but I'm 6.2 tall and weight 195lbs, and over the years have ridden allot of centuries, double centuries, and plenty of brevets. I think it's safe to conclude that if there was a problem with 753 tubing I would have experienced it buy now.

Tom Harriman San Francisco, (having a Mark Twain summer) Ca
> Date: Tue, 6 Jul 2010 12:58:57 -0700
> From: jameshmerz@gmail.com
> To: gillies@ece.ubc.ca
> CC: classicrendezvous@bikelist.org
> Subject: Re: [CR] Frame stiffness NOW Frames Getting Soft and 753
>
> Heat treating does not increase the stiffness of steel. All steel no matter
> the alloy or heat treat has the same modulus of elasticity (it can change
> slightly with high percentage alloys). Heat treating increases the tensile
> strength and hardness. Your 2nd point is also incorrect. Annealing does make
> steel softer, but it does not increase the fatigue limit. Think of a steel
> spring, very high tensile material, very high fatigue limit. Tubing used for
> a bike frame should be considered a spring.
>
> Your comment on glass has no bearing with this discussion. Glass is plastic
> with no crystillyn structure. Most steel is made of crystals. Bike frames do
> not anneal during riding. Even if they did the stiffness would not change.
> What does happen during use is very small cracks can start forming. After so
> many flexes these cracks can grow and then the tube will fail. At some point
> in time when the crack goes clear through the tube the frame stiffness will
> decrease. In no other case will the stiffness decrease from riding!
>
> Jim Merz
> Big Sur CA
>
>
>
> On Tue, Jul 6, 2010 at 12:34 PM, donald gillies <gillies@ece.ubc.ca> wrote:
>
> > Well, I don't believe that 531 tubing can 'get soft', but In theory a
> > heat-treated frame like 753 could possibly 'get soft', and here's why:
> >
> > My understanding is that 753 tubing was just thin 531 tubing that has
> > been heat-treated, i.e. heated to high temperature an then quenched
> > to rapidly freeze the grain structure in the random pattern obtained
> > at high temperature, thereby stiffening the tubing:
> >
> > http://en.wikipedia.org/wiki/Quench
> >
> > The opposite of Quenching metal is annealing, i.e. heating metal to a
> > high temperature and then slowly cooling it back to normal
> > temperature. That reorganizes the grain structure making the frame
> > less-stiff but more resilient and increasing the fatigue limit.
> >
> > http://en.wikipedia.org/wiki/Annealing_(metallurgy)<http://en.wikipedia.org/wiki/Annealing_%28metallurgy%29>
> >
> > ====
> >
> > Well, it turns out that the frame is annealing itself all the time,
> > from the heat at room temperature. If you have ever looked at a piece
> > of glass that is 100 years old, you can see ripples and lumps in the
> > glass. This is not from a poor manufacturing process 100 years ago,
> > in fact, 100 years ago the glass was perfectly smooth, but in the
> > intervening 100 years the glass has "gone soft", i.e. it has
> > integrated enough thermal vibrations into its grain structure to melt
> > slightly and change shape, i.e. it has annealed, slightly.
> >
> > The same thing is happening to Reynolds 753 all the time. The more
> > heat the frame gets, the more likely the frame will 'anneal'. In
> > fact, the degree of annealing is probably equal, almost, to the
> > integral of all the heat the frame has absorbed since it was
> > originally heat-treated.
> >
> > ====
> >
> > The conclusion is inescapable. First of all, don't buy any Reynolds
> > 753 frames from Texas or Arizona! And secondly, when not in use, you
> > should store your reynolds 753 bicycle in a refrigerated meat locker!
> > Nothing less preserve the ride characteristics of your frame and keep
> > it from going soft !!! :-) :-)
> >
> > - Don :-) Gillies
> > San Diego, CA, USA