Picked up my new Vado 4 today Sat 4/25 and went for a 24 mile ride. I didn't hear any grinding noise just the very low growl that Sierratim mentioned. Had a good ride, went out with my daughter and son-in-law who were both on road bikes. My 72 year old body would never have kept up if not on the Vado and kept it on low levels almost the whole time. Bike needs to go back as when I put on my glasses to see what the blinking message was telling me I have a battery error. Hopefully I won't be w/o a bike for long.