Here's the best of the rest of the pics of Robic's 'cross bike, here seen crossing the line to win the 1950 World Cyclocross Championship:
http://www.wooljersey.com/
I see a cable housing curving from the left bar-end shifter, around the he and then following the top tube. I also see a rear derailleur shift lever on the downtube, front derailleur or chain guide, two dark handlebar clamp bolts, wing nuts up front. From "Miroir Sprint" No.195, 6 March 1950.
I'll keep looking for more pics.
Aldo Ross
Middletown, Ohio