The rear brake is mounted under the chain stays, so brake bridge isn’t necessary.
Recently, local and well known frame builder actually asked me if the frame was stiff without the brake bridge. I told him yes it’s very stiff, and the bridge doesn’t add stiffness. His was,
“Then why do frames have them?”
“To hold the rear brake” I said.
“I’m not sure I believe that” he finished.
At that moment I realized frame building is a art, science and religion.
Between December of 1989 and January of 1990 the Braunstein-Quay Gallery in San Francisco hosted a show called The Art of the Mountain Bike. A number of Northern California mountain bike frame builders were asked to put together their most artistic versions of their work, which were displayed at the gallery.
This is the Otis Guy from that exhibit…rescued from 15 years of obscurity, boxed away in a hoarders collection, it’s restoration finally complete.