a fellow framebuilder asks,
>"...but how do i explain the 1 1/8" thing to my client?"

tell your guy that 1-1/8" steerers were a solution to a
problem caused in the 80s (?) when standard road
dimensions were used to build the 'newfangled' off-road
bicycles...and the results merited some rethinking.

continue with...
and in time, the industry embraced the dimension for all
uses because it was easier to cater to the lowest common
denominator: the intersecting paths of time and money.

if your guy is bright, he'll 'get it', and defer to your
suggestions, because, of the two people involved in
this equation, you know more.