Not needing a rack , i have a Blackburn the holy grail of racks in uk but it has stays and fits on to welded lugs it is always on my Alves analogue bike. . Dont think i would ever try to fit rack to ebike .Those racks are the Topeak Tetrarack. For heavy loads a proper rack that attaches to a modified axle would be best. These axles make it possible: Bicycle Thru Axle Finder 100% Guaranteed! - The Robert Axle Project