I have a pair of these CLB levers (the same ones as on the velo-orange site) and i mounted them on my daily rider city errands bike.
They fitted a pair of guidons phillipe training bars but the bars needed some filing inside since they were a tad to big. I have another spair pair and can measure. I do not know whether these are the same as on Velosolexes but they look the same in the picture. I tried a couple of bars but most other bars were simply not big enough - the bar walls were just to thick. Those old french training bars are really light, I destroyed one pair pulling to hard on a climb on one side. I just snapped where I drilled it for the brake cable.....