Guy in work here is selling a pair of Thule roofrack mounted bike carriers that came on a car he's bought. They sound quite old, so I imagine they might be the Thule 575. He isn't sure, but says that they have a U bolt mounting. My Thule rack is AERO bar profile, and "needs" the bike carrier to use the "special" mounting bracket that slides into the slot on the upper surface of the rack. I am worried that the carrier mounts will be too narrow to go around the aero profile. I have to make an awkward journey into the middle of Swansea to view them, so any advice here would be grateful (I hate Swansea)..... Thanks.