Would love to help, but have never used either of those racks before (mine is only rated for 40 lbs, which does the job for me).
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Bikes: 1996 Eddy Merckx Titanium EX, 1989/90 Colnago Super(issimo?) Piu(?), 1990 Concorde Aquila(hit by car while riding), others in build queue "when I get the time"