My Aventon Aventure has a steering Shaking/oscillating problem. This started after about 2500 miles. I had the bike shop check it and they put in new head set bearings. That did not fix the problem. I had Aventon send me the complete head set and the bike shop installed that and it still shakes. It is not a speed problem as it will do it at any speed. You can actually just grab the handle bars while it is stopped and shake the bike and see/feel the bike oscillating. There is no play in the headset and every thing is to specs. They can't figure out what is causing the oscillations even when it's standing still. Any ideas?