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


Example: Books:Ron Kitching

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Date: Tue, 6 Jul 2010 16:29:24 -0700
From: Jim Merz <jameshmerz@gmail.com>
To: WILLIAM HACKETT <wfhackett@cox.net>
Cc: Classicrendezvous@bikelist.org
Subject: Re: [CR] Frame stiffness NOW Frames Getting Soft and 753


I never saw anything from tubing makers regarding tubing recommendations. Maybe 531SL had some rider weight limit, also these really marginal tube sets did not come in larger sizes. Because steel bike frames have been made for so many years there is quite a bit of experience with what works and what doesn't. I had the chance to see bike frames made throughout the world when steel frames were the norm, I never saw much testing. Most production frames were made with conservative tubing choices. Real testing of bikes did not happen until after new frame materials started coming into use. When you change to a material that has never been used for making bikes it becomes very important to know if they will be safe. And it is not such a good idea to have the customers do your testing by using the bike. The large bike companies will not send any frame out the door without really serious tests on the frame.

Jim Merz Big Sur CA

On Tue, Jul 6, 2010 at 4:03 PM, WILLIAM HACKETT <wfhackett@cox.net> wrote:
> Gentlemen
>
> Fatigue properties and working stress are factors involved. The Bike Frame
> is stressing everytime it is ridden. Any tubing will break if it is stress
> often enough. Even if the stress is well below the failure properties of the
> material.
> Self Annealing of steel without heat over long period of time is not
> likely.
>
> There must be a Reynolds Handbook that recommends working stress and
> factors of safety, for each tubing and method of assembly.
>
> It is likely that some Frame builders would take materials to design
> limits, to have a best and most competitive Racing Frame.
>
> The special frames would be retried.
>
>
> Bill Hackett, Mesa Arizona
>
>
> ----- Original Message ----- From: <billydavid13@comcast.net>
> To: "donald gillies" <gillies@ece.ubc.ca>
> Cc: <classicrendezvous@bikelist.org>
> Sent: Tuesday, July 06, 2010 3:18 PM
>
> Subject: Re: [CR] Frame stiffness NOW Frames Getting Soft and 753
>
>
> Hi Donald, all. This discussion's a bit over my head. But, as per Don's
> suggestion i always keep a couple of cold ones in the 'fridge. Cheers. Billy
> Ketchum sweltering in Chicago, IL; USA.
> ----- Original Message ----- From: "donald gillies" <gillies@ece.ubc.ca>
> To: classicrendezvous@bikelist.org
> Sent: Tuesday, July 6, 2010 2:34:07 PM
> Subject: Re: [CR] Frame stiffness NOW Frames Getting Soft and 753
>
> 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