Yeah it might be because you chainring is bent, the same thing happened to my friends motobecane. You can bent them back quite easily, but it does make it weaker. The gay thing is, the old peugeots chainrings are attached to the spider/cranks! So you might have to get new crankset, the works! Do try bending it first, as there is less force running single speed, it might just work out for you. good luck.
Yeah it might be because you chainring is bent, the same thing happened to my friends motobecane. You can bent them back quite easily, but it does make it weaker. The gay thing is, the old peugeots chainrings are attached to the spider/cranks! So you might have to get new crankset, the works! Do try bending it first, as there is less force running single speed, it might just work out for you. good luck.