I've noticed at lower speeds (10-20 km/h) the front end makes a rhythmic noise. Hard to describe, but kind of like a rhythmic howl. The faster I go the noise increases but goes away at any speeds over 50 km/h. It's strictly a noise for now as far as I can tell. I can't feel any sort of vibration that would correspond to the noise. I checked the tire over and couldn't see anything wrong with it. Any ideas?