Well, according to Easton, they say not to use a 4-bolt stem on a CF handlebar due to the possibility of uneven torque on the bolts causing issues with the bar. While I suppose that's a possibility, people here are using 4 bolt stems with carbon bars without issue. I think Easton just wants to be on the safe side. I personally just find CF bars to be ridiculously overpriced. The FSA K-Wing (240g) is $199 from repartocorse.com and the Easton EC-90 Equipe (185g) is $179.95 from lickbike.com. Kestrel has a 180g road bar (EMS-SL) for $169.99 @ repartocorse. The Deda Newton is $115 and weighs about 200g. Seems that the lure of carbon fiber isn't in the weight.