Jandd or Blackburn? It maybe that the racks are designed with that much clearance for a reason? Also the eyelet mounting points play into it. FWIW I just checked a couple of pictures of my Giant Iguana, the Blackburn rack sits the closest to the wheel, the Jandd is way up. Doesn't bother me at all.
I have used both in the past with no problems and they were specifically sized for a 26" wheel.
Aaron
Jandd Expedition Racks
Blackburn Rack