I have a 2002 Roadhawk trike. I am getting a vibration when I get to around 1700 rpm. It seems to be from 1700 to around 2100 rpm. It isn't a steady vibration. I am not sure how to explain it. It almost feels like a drive line vibration like a driveshaft bent or something but it can't be that since I don't have one. It is fine below 1700 and seems to go away about 2100 rpm. I can feel it through the handle bars but not through the seat or foot brace. I have had the trike for a year and a half and i didn't notice it doing this until a few months ago. Wonder if it could be my tires causing a vibration at this rpm. Any suggestions or questions would be appreciated. Thanks