The other problem was the length of the lever arm which meant that for six inches of travel of the lever the brake blocks moved 5mm.
Unless they were very well adjusted with the blocks close to the rims (and a very straight wheel) you could pull up on the upper levers and the blocks never reached the rims. Blooming nightmare to set up, hated them !! Manufacturers called them "GT Levers".......which was on the boot of the top Cortina's of the day LOL
As I mentioned, parents loved them because they could be operated off the drops. For some reason parents were worried about kids with their heads down running into parked cars...........with these levers they had a greater chance of not stopping at all
PS Does the frame have a built in kickstand, a plate attached to the chainstays behind the bottom bracked ?