the zipp Z series weighs 1067 g for the Z3, 1270 g for the Z4, and a whopping 995 g for the Z2. Z4 is the deepest most areo rim, Z3 is in the middle, and Z2 is normal depth rim. they have some sort of really low friction ceramic bearings. check 'em out at competitivecyclist.com. all of them are tubular. the wheels themselves may be really light, but they won't be on your wallet.