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.

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.

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.

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.

Steel with chromium and molybdenum is called "Cro-Mo".

2040 tubing is "No-Mo".

Sorry, I couldn't resist.

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).

Just weighed a stripped 62 cm (c-c) 2040 frame, no fork. Came in at 2,98 kg which is quite heavy.

2040 steel is a European Designation, and long outdated now...it was known for stiffness due to the high carbon content, and it also resisted heat hardening when brazed or welded, negating the need to anneal the frame after joining.

most other high carbon steel alloys readily harden when heated to a glow, then cooled.... hardened steel becomes BRITTLE steel... Brittle steel likes to Crack at high stress junctions.

Hopefully the OP has the old Motobecane sold by now. :D

High tensile is about the lowest grade steel you will find on a bike.
Anything "weaker" would have to have a much greater wall thickness etc. that the weight gets prohibitive.
Santa would be giving bikes that outweighed the kid.

OP last posted in 2007.

Just finished refurbishing a Motobecane Sprintour, a rather lower of the line bike originally. I like the ride; kind of softer than my Grand Record and Super Mirage. With the higher end components (Campy hubs, seat post and derailleurs, mostly Moto for other components, it weighs 28 pounds (obviously without bags and lights). I do not have anything against the 2040 except for my deep seated snob appeal...
https://cimg1.ibsrv.net/gimg/bikefor...57c3976d0a.jpg

I stand corrected.

Raleigh used what they called 1020 tubing at one time for their lower level road bikes. We use to joke that the 2040 French tubing was twice as good:)

I never placed too much value on much of the bike brands' tubing claims, excepting second party brands with their own trademarked decals like Reynolds or Columbus. Even then there are cases when the only tube with the claimed material was the one with the decal. Andy