Hi, I bought a new bmx bike a few weeks ago. When I first bought it I could take it off a jump and take my feet off the pedals to do a trick and the pedals would stay in the same place and not move even though the rear wheel was still spinning. Now when I do the same thing the pedals keep spinning. I was just wondering if I have stuffed the bearings or something and if there is anything I can do to fix it? Thanks 