Hello, everyone: As a new member, I really appreciate the existence of this site. I have a 2015 c650GT, a month ago at around 4000 miles it developed a strong vibration between 5-10 mph accompanied with a metal screeching sound. The vibration seems to come from the chain drive compartment (rear).It only does it between 5-10 mph , once it is over 10 mph, bike drives great with no problem. Also, it often happens only during cold start (in the morning after garaged it for overnight or extended period of time). The vibration tend to disappear as the scooter gets driven during the day. Took it to the dealership, they replaced the roller, roller housing, and guide as instructed by BMW after 4 weeks under warranty. The second day after getting it back, it did the exactly the same thing again. At this time the dealership is clueless on what is going on. Can anyone help please, losing summer driving time up here in New England! Thank you all! God bless!