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.