Ask Dr. Science

  As an emeritus professor of metallurgy, I was disturbed to see the promotion of bamboo bike frames relative to steel frames in the "Snapshot" section of the June 11 issue (HCN, 6/11/07). Steel is referred to as "carbon-intensive" in that note, but steel is not carbon-intensive. Steel is mostly iron, an abundant element, that contains a very small amount of carbon, depending on the strength level desired. For chromium-molybdenum (chrome-moly) alloyed steel, from which rugged steel bike frames are manufactured, the carbon content is typically only 0.3 percent. While the very low carbon containing sheet steels used for automotive panel applications are manufactured with coke derived from coal, almost all of the bar steels used for tubing and shafts are now made from recycled scrap steel in electric furnaces that use no carbon in the melting of the scrap. Steel is therefore highly recyclable and can be used again and again once it has outlived its original use. It appears that the "Snapshot" note was trying very hard to justify the $3,195 cost of a bamboo bike frame compared to the few hundred dollars cost of a steel frame.

George Krauss
Evergreen, Colorado