anyone experience or know if normal for there to be a hmm,, how to explain this, it is as if i am running on slightly bumpy road or more accurate as if the motors are shuddering only at 77km to 85km, there is no noises just a feeling of shuddering, my wife said do we have a flat tire the first time. As far as I recall it has always done this so i felt it was maybe a harmonic imbalance of sort at that particular speed. I am not finding anyone else mentioning this.