I recently came across an early 80s Fuji that was labeled as having a "Quad butted Cromoly 9658" frame. I only had heard of up to triple butted at that time. How is this different and whats the number signifigance?
Thicker at the ends. Said of spokes and frame tubing. (Butted spokes are also called "swaged") Butted tubing is usually made with a constant outside diameter, but thicker walls at the ends. The idea is to make the part stronger at the ends, where the stresses are greatest, and lighter in the long middle section, where stresses are less. Some writers have objected to this term being applied to spokes, and maintain that "swaged" is more correct, since the operation that produces a butted/swaged spoke is one of thinning the middle, not thickening the ends. For some reason they don't generally object to the use of "butted" in reference to tubing, though the process is also one of thinning the middle, not thickening the end. This objection is based on a misunderstanding of the origin of the origin of the term "butted." "Butted" means having a butt, i.e. a thick end, and has no reference to the means of fabrication.