I tried posting this in the Mechanics forum but surprisingly didn't get any answer so I thought I'd try here - these stems must be popular for putting on vintage bikes (heck, I've got a different Nitto on MY vintage bike!).
I'm researching stem options for a new frame I'm having built. Trying to decide quill or threadless, some geometry issues, etc.
Anyway, that's not the point. I've been looking at the Nitto Dynamic stem. The descriptions all (just) say "A=45mm, B=78mm" plus a length (80mm, 100mm, whatever). Now I know A and B have to due with height and insertion and at one point I actually knew what A and B were but now I can't get my head around it. Can someone refresh my memory about what the A and B measurements represent?