I was helping my brother in law put together a cheapo BMX for my nephew and it had a weird disc mechanism wrapped around the stem/steerer tube. The brake cables ran to it, terminated, and then a new set of cables run to the rear brake. It appears this 'plate mechanism' acts as an intermediary for pulling the cable. We couldn't get the brakes to function correctly with it, so we bypassed it and used cable ties to run cable outer to the rear brake along the top tube. What is this mechanism for? Having only worked with mountain bikes and road bikes, it's not something I have come across before. Googling it comes up with something called a gyro plate. What function does it serve?