Hi, i am from Turkey.
I need some help. I have a bike which belong to my father, i like to restorate it. But i have no a brand name for searching clue, only there is characteristic sign "S" on the frame where the rear brake is mounted (You can see in the picture). Also there are "Weinmann" brake set; shifters and derailleurs are "Sachs". It could be a european bike, the time period is 1970's. Could you help find the bike's brand name?