Ishiwata and Tange tubing

From the retrogrouch :-)

http://bikeretrogrouch.blogspot.com/2014/01/classic-tubes-tange-and-ishiwata.html

The common alloy used for bike frames were chrome-molybdinum which is referred to as ChroMo. I didn't know Manganese was used on some tubing until I ran into this blog. The alloy is called Mangy.
The link above shows how the Ritchey Logic came out of the Tange Prestige tubing.