What does 531 tubing look like?

Question

I've got a bicycle and some of the paint has come off. Underneath the bare metal is a shiny grey colour and it hasn't rusted at all even after being out in all sorts of weather.

Does this sound to you like 531?

Answer 1

531 refers to Reynolds Tubing and the alloying components. It is a steel compound. the 531 is the ratio of alloying components in the the frrame. 531 is approximately 1.5% Manganese, 0.25% Molybdenum, and 0.35% Carbon. The rest of the material is Iron. Check your frame with a magnet. 531 is magnetic and the magnet will be attracted to it. Reynolds 531 will rust when left out in the weather. Most frames have a label listing the frame material. Reynolds 531 is not very common anymore as a bicycle production material. In the 1980's this material was very common.

Answer 2

Aluminum is usually a light silvery metal. It won't attract a magnet, doesn't rust and usually comes in relatively fatter tubing diameters. Reynolds 531 is a steel alloy that rusts. Most bikes made with Reynolds or Columbus (or Tange or Oria or Deda) tubing have a small sticker somewhere on the bike, usually on the seat tube, stating the kind of tubing used. Columbus also came out with Metax tubing which is stainless steel and doesn't rust (there are other makers of stainless steel tubing too).

Answer 3

Reynolds 531 tubing was by far the most popular for performance bikes into the late '60s. It's an alloy steel made with manganese/molybdenum. It will rust.
Bike tubing made from aluminum or titanium won't rust.
Not knowing the age or maker of the frame, I can't say what you've got, but most probable guess is aluminum, based on more aluminum bike frames in production than titanium.

Answer 4

531 was commonly used by Reynolds tubing and went on higher end road bikes of the 70's, 80's like the Raleigh Pro

Answer 5

I think 531 refers to the guage which has just enough flex to be good enough for top quality bikes. I don't think it is rustproof but I could be wrong .