Do any of you experience any unusual sounds from the Ultra motor when under power (pedaling or throttle). If so, how would you describe the noise. I have a sound similar to fine grade sandpaper on metal. It is not real loud but can definitely be heard. It is apparent whenever the motor cuts in and is definitely from the motor. Since I never had a mid drive before I am not familiar with the sounds the motor makes. I have a 750 watt rear hub motor ebike and that motor is silent.