Giant Defy compatible with Thule bike rack?

mjf1017 Posts: 48
edited June 2014 in Road buying advice
I need a bike rack for my Giant Defy 1. I'm looking at the Thule 591.

Does any one use this bike rack with a Giant Defy. The aluminium frame is almost box like rather than round and I'm not sure if it will fit. If not, can anyone recommend a bike rack for modern road bike frames?

Thank you.