Is there much weight difference between the equivalent Defy advanced and TCR advanced bikes (assuming same components on both bikes)
It will be minimal, the real difference is the geometry, and how the bike fits you. A few ounces can never compensate for fit.
I have a single track mind
tcr advanced is more race oriented while the defy advanced is more upright position (recreational riding). i would say the weight will be almost the same if both are equipped with the same components.
when i was shopping for a giant frameset, i was told (advise) that if i am not racing, i should get a defy and not the tcr.
I have the 2010 defy advanced 2 with full shimano 105 set and maxim aksium wheels. Without pedals it's 18.06 pounds.
What about the Composite compared with the two?
From my research the Defy and TCR advanced are the same carbon guts and weigh the same. The composite is a different carbon construction that weighs more.
Side by side at my LBS I could feel a noticeable difference just lifting.