I'm new to disc brakes and trying to figure out what I need to buy to buy them for a wide fork (135 mm dropout spacing) with IS disc brake mounts and an electric front wheel. I've researched, but I haven't found any information that specifies a standard distance between the I.S. front disc brake mount (i.e. where the disc brake caliper attaches to the fork of the bike) and the disc brake rotor.
Given that getting this distance correct is crucial, since a few millimeters distance is all it takes for the rotor to rub up against the caliper pads, I would think there would be a clear standard distance, but I haven't found one.