In the case of Cinelli 42cm width bars during the CR period, they bent down with use. After some time they would break. I always used the wide bars back then anyway. Specialized sold Nitto made bars that were copies of Cinelli and were available in wider sizes. I imagine these are impossible to get now, but Grant Peterson sells some Nitto models.
Jim Merz Bainbridge Is. WA
As for the narrow bars on older bikes, I always heard that "space in the
peloton stuff," even in the 1980s. A real crit-meister uses skinny
bars to fit through the gaps in corners and sprints! Whatever. Anyone
have some old-logo 66-42's to sell cheap? I'll be non-period, gladly.
Funny how rare those are. I guess they really did mostly use 40's back
then.
Tom Dalton
Bethlehem, PA