Just found this while searching for another item. The clunk is when the bike is going faster than your legs so the engagement point of the freewheel is random. The fix for this is a technique while coming out of coasting best described as the practice of ghost pedaling while slowly increasing rate until light engagement takes place. I’ve got 6500 miles on a 2019 City and have put lots of thought and practice into this. Any regular bike will clunk if you don’t speed match gear, speed and pedal rotation speed closely. Ebikes are worse because of the higher speeds vs leg and gear speed. As posted, some expensive bikes have a better freewheel or free hub that reduces this.
