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Tubing is the heart of a bicycle frame. Tom Teesdale uses two tried and true materials to build custom frames. Steel and Aluminum. Both materials are ideal for frame construction, with slightly different properties.
A little history...for years the diameters of the
main tubes in steel frames were 1" tt,1.125 dt & st. Alloys were chrom moly(Columbus) or ChromManganese (531). Wall thicknesses were 1x.7, .9x.6, .8x.6. tensile strengths ran 100000 to 130000 psi
With the advent of higher strength steels that were ductile enough for bicycles (9% min.) starting with Tange Prestige and Reynolds 753, manufacturers of tubing have been able to decrease the wall thicknesses without failure problems. But the "stiffness" of a piece of tubing is dependent on diameter (and cross sectional profile) and wall thickness, not on the type of steel. So to take advantage of the thinner wall thicknesses the diameters of the tubing have been increased to keep the frames from being noodles. Today road bikes are commonly 1.125 top tube & seat tube, 1.25" down tubes. Wall thickness of .65x.4, .7x.4, .8x.5, .9x.6 are in use. Tensile strengths of 170000 to over 200000 are now available. I doubt steel tubing will ever get thinner because of the "tin can effect", denting and buckling.
Here is a listing of some of the most available cycle tubings
Reynolds tubing
531 - has been all but retired in favor of the following steels. Each one is available in a range of diameters (1" to 1.5" od) and thicknesses (.7x.4 to 1x.7)
853 - air-hardening steel, goes over 200000psi at the weld
725 - heat treated chrom moly
525 - chrom moly (takes the place of 531)
Columbus tubing
Columbus is probably the most innovative of the tubing makers. They have concentrated on alloys and complex heat treating processes that maintain a fine grain in the steel and maintain higher strength through the anneal areas next to the welds. They also do a lot of manipulation of the interior butting of the tubes in the sets with what they call "differential butting". Wall thicknesses are increased in areas like the waterbottle mounts and front derailleur mounting areas. The main butts are shaped like spear point lugs, only on the interior. They also do more tube profiling in their sets than anyone else, ovals, bulges, grooves, etc. Each of these "sets" contain a number of wall thicknesses and diameters to choose from.
Focus - Thermacrome steel-their top end, an enhanced version of Nivacrome. Like the 853, final ultimate strength is after the welding takes place but without the extreme hardness that 853 developes.
Nemo Road - Nivacrome-differential butting-An excellent steel, close to 853 (853 before welding) in strength.
Genius - Nivacrome-differential butting
EL - Nivacrome
Brain/Thron - Cyclex/Cromoly
Easton tubing
sc7000 - Scandium alloy of 7005 aluminum, approx 40% stronger than 7005. The scandium causes the grain structure to be very fine and uniform throughout the frame including the welds (must be welded with scandium welding wire). The weight is saved by reducing the wall slightly and tapering the od of the tube. (large at the head tube, then tapering to a smaller diameter)
7005 - when it comes to aluminum no one can touch Easton. Aside from the fact that 7005 alloys are stronger than the 6000 series, they really have the butting process down for aluminum. They are dead smooth on the interior with larger transions in wall thickness than anyone else can do. They really do ride smoother than most other aluminum frames.
