It makes the knocking on any surface. Perhaps it's the rear brake line as I have axs.Does it only make a noise when you are freewheeling on rough ground? If it goes away when pedalling on rough ground I think it may be backlash in the motor. I had this with mine and its perfectly fine according to LBS
Thanks so much for chiming in. I appreciate it! The sound is coming from an area close to the bottom bracket. Perhaps it's the rear brake line?@AlexEMTB With our bikes most (if not all) cables in the frame are pretty carefully routed/protected to prevent this being possible. If it seems to be coming from somewhere around the top-tube area and particularly evident when going over slightly uneven ground at speed then it's worth checking the headset bearings. Remove, clean, regrease liberally unless grinding, seized or rusty.