As I speed up, around 15 mph or so it seems to disappear, as I slow down like at a stop sign I hear it again. I think when I am traveling, the sound is there, but it is not audible due to the speed. It does not change with road variations or with bumps. Only squeaks when going forward and when starting out and slowing down. Does not squeak in reverse. Squeak sounds like a rubbery squeak rather than metal. Hope this helps and thanks for your info.