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

(Example: Framebuilding:Brazing Technique)

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References: <> <87DF243CE43143E68614A3D282FA5F95@laptop2> <>
Date: Tue, 6 Jul 2010 18:02:47 -0700
From: "Jim Merz" <>
To: Angel Garcia <>
Subject: Re: [CR] Frame stiffness NOW Frames Getting Soft and 753

Yes, this test was common in the day. I am not talking about this kind of crude setup. No way can the loads be controlled correctly with this brute force setup. These days the test fixtures will use computer controlled MTS dynamic test units. Big "S" has more than 10 stations of these running 24/7 with real engineers tending to the multi-million dollar lab. I have great respect for the results from 100 years of real world experience that defined steel bike frames. But in order to take frame design to the next level real engineering is a must.

Jim Merz Big Sur CA

On Tue, Jul 6, 2010 at 5:49 PM, Angel Garcia <> wrote:
> re: frame testing: I did come across a photo of a Bianchi test jig in 1981:
> you can click on photo to enlarge it.
> Angel Garcia
> Long Valley NJ
> ---------- Forwarded message ----------
> From: Jim Merz <>
> Date: Tue, Jul 6, 2010 at 7:29 PM
> Subject: Re: [CR] Frame stiffness NOW Frames Getting Soft and 753
> Cc:
> 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