John B. Slocomb wrote:

Is it more thick at the bottom of the bottom
bracket shell and at the bottom-mid section
of the down tube where I have seen this
numerous times, and also the chainguard
stays to the chainguard intersection?

A bottom bracket is usually specified as 7 -
8 mm thick.

And the mid-bottom part of the down tube?
The screws are interchangeable in size
and length.

Yesterday BTW I saw a second bike with the
exact same configuration. The bracket is bent
so it is round along the tube surface, but what
holds it in its place seems to be a single M5
screw with a flat PZ2 head.

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