Originally Posted by
fietsbob
You spread the rack wider at the bottom, to gain clearance for the disc brake
caliper, and use spacers around the bolts, to fit them onto lower mounting spots.
alternatively move the rack backwards to make the space for the caliper.
The OP already has a rack, but needs help to either lower it or finding a suitable substitute that won't have as much daylight between the rack and wheel/fender
