I changed my tires and my chain/sprockets(oem) in one go, and now I get a weird vibration. It's not so much of a buzz as it feels like someone doing a drum-roll on my handlebars. I feel the vibration between 60-70 mph, but only in 5th or 6th gear. The frequency of the vibration changes between these two gears. I feel roughly 8 taps per second in 5th, and like 2-3 times that in 6th. I feel it on acceleration, deceleration, but not with the clutch pulled in. No vibration in any other gear at the same speed or rev range. I'm at a loss. Maybe someone can help me figure out what this is?