Because the guide from the rear brake is connected to an exit on the left side of the frame on the downtube (i.e. for conventional hose arrangement), rather than routed for internal routing via the head tube.
It feels like some sort of woven fabric so it's entirely possible I can just get some scissors in there but I'm loathe to do anything (too) stupid on a brand new frame.
Because the guide from the rear brake is connected to an exit on the left side of the frame on the downtube (i.e. for conventional hose arrangement), rather than routed for internal routing via the head tube.
It feels like some sort of woven fabric so it's entirely possible I can just get some scissors in there but I'm loathe to do anything (too) stupid on a brand new frame.