I had a Cannondale rental road bike stolen in France. The rental agency claims it was an Evo super six 105 full carbon. I do not believe that is correct because the top cross tube was very large and round like aluminum bikes I have ridden. Perhaps this had carbon forks but aluminum frame? If so can anyone suggest what model it might have been? Again the top tube was perfectly round and probably about 2" outside diameter or maybe a little less. Are carbon tubes large and round like that?