I highly recommend the guys at Trek Gwangan. I have been bike packing in Korea for the last 2 weeks and After more than 1200km my bike, and particularly the rear hub, was in a very bad state and need of a check. The service provided by Yuan was nothing short of amazing. He degreased and cleaned the pawls and the cogs of the rear cassette and put everything back together in not time. My bike now runs as brand new! Thank you for your amazing service and friendly approach!