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Old 07-26-05, 01:23 PM   #1
CalTex
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I am selling a Motobecane Super Mirage frameset with 2040 tubing. I would like to, at least, appear knowlegeable about the material when approached by prospective buyers. I have done exhaustive research on Google and can only find that it is "high tensile steel". Is there more that anyone has to offer as to the composition of this 2040 material, the frame construction, or even this frame as relates to Motobecane Super Mirages? If dating the frame is of use, there are pictures available at http://www.doug-morgan.com/BikeSales/Motobecane.html and it came with a Sun Tour V-GT Luxe rear derailer and Weinmann center-pull brakes. Your assistance in this matter will be greatly appreciated.

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Old 07-26-05, 01:49 PM   #2
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If I have my numbers right, that's a high-carbon nickel steel, but no chromium. This I believe makes it heavier and softer than a crmo steel.
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Old 07-26-05, 03:43 PM   #3
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Quote:
Originally Posted by CalTex
I am selling a Motobecane Super Mirage frameset with 2040 tubing. I would like to, at least, appear knowlegeable about the material when approached by prospective buyers. I have done exhaustive research on Google and can only find that it is "high tensile steel". Is there more that anyone has to offer as to the composition of this 2040 material, the frame construction, or even this frame as relates to Motobecane Super Mirages?
Right above gas pipe as far as material for bike frames goes. Ok for bridge girders,but somewhat pricey for boat anchor material. Just say 'steel' and let it slide.
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Old 07-26-05, 03:56 PM   #4
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In the 1970's, some steel tubing used for bikes was a bit lower in strength than cro-mo, even when sold in double-butted form for use with lugged construction. So, to build a frame that was equal in strength to a four-pound frame made from cro-mo, the frame ended up weighing about one pound more.

But, it was used on lower levels of bikes, with heavier components, and heavier wheels. On a 28 pound bike, it would have been silly for the manufacturer to spent extra money on "fancy" tubing such as Reynolds 531, just to end up with a 27 pound bike.

The REALLY heaving stuff was the steel used on Schwinn Varsities. They ended up weighing about 40 pounds. In comparison to a Varsity, a 28 pound Motobecane was a "feather weight" bike.

I have found when buying older bikes that I can buy a bike with a Reynolds 531 frame for about the same price as a bike with a generic frame. Given the choice, I would go with Reynolds over generic steel...but some good bikes have been made with those heavier types of steel.
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Old 07-27-05, 09:35 AM   #5
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Steel with chromium and molybdenum is called "Cro-Mo".

2040 tubing is "No-Mo".

Sorry, I couldn't resist.
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Old 07-27-05, 12:28 PM   #6
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The 2040 steel was 1 step down from cro-moly in the Motobecane line back then. I had this model bike and it dates to the late 1970's. As best I can remember, threading was a mixture of French and Swiss (a real pain).
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