วันจันทร์ที่ 9 มีนาคม พ.ศ. 2552

Discuss : Cromoly 4031 vs Reynolds 531

This is discuss about Cromoly 4031 VS Reynold 531 from another Forum

- chromium molybdemum (sp.?) is an excellent steel alloy, and the 4130 denotes a specific forumulation of alloy (like 6061 aluminum is a specific alunimum alloy, as is 7005, etc.). Not all chromoly steel is specifically 4130, but you see it pretty often. I have a friend who is an aircraft engineer, and he says 4130 steel is usually used in aircraft when steel is needed. It's incredibly strong, and relatively lightweight. Reynolds 531 is a proprietary steel alloy of Reynolds, and it is manganese molybdemum, I believe. Reynolds claimed this to be superior to chromoly for bicycle tubing. The main thing about something like Reynolds 531 is in the way they manipulate (butting, shaping, etc.) the tubes, and there is a wide variety of 531 tubing for frame builders to choose from. In other words, a touring bike made of 531 would more than likely have a different 531 tubeset than a racing bike, etc. Reynolds has since come out with 501, 555, 753, 853, etc. All of them are steel, and all of them have their own characteristics. For a long time, 531 was their best.

- In theory, bicycle tubing could be made with 4130 steel that is similar in weight and strength to Reynolds 531. For years, 4130 tubing was standard in the American aircraft industry, just as Reynolds tubes were used in British made aircraft. However, marketing is always more important than engineering. A 4130 tube is generic, and therefore of little marketing value. So, bike makers of the '70's and '80's preferred to use tubes that could be promoted, such as those from Reynolds and Columbus.

When companies in that era used 4130, they often used straight gauge tubes of medium weight. They COULD have asked suppliers to make double-butted, thin walled 4130 tubes, but that would be pointless. Those sorts of tubes were already being supplied by Reynolds and Columbus.

So, although it is possible to make a light weight 4130 frame that is as strong as a light weight Reynolds frame, the 4130 frames that were actually buillt often weighed a pound or so more than a Reynolds frame of the same size. And, the Reynolds frames were often on top-of-the-line bikes, so they were set up with lighter, more expensive components. The 4130 frames got heavier cheaper components. In 1974, a company that was selling a 23 pound Reynolds bike might have also sold a much cheaper 28 pound 4130 bike. But, it was NOT impossible to make a 23 pound 4130 bike...just no motivation.