I have a 2009 Giant Trance with an internal cup headset with a 44mm headtube diameter. I was planning on converting it to a tapered headtube by using a Cane Creek 110 conversion headset which fits a 44mm ID headtube, but has the bearings outside the headtube like a traditional headset so a 1.5 headtube (40mm) will fit. In theory this should work, but the bike shop I went to said it wouldn't. According to them the headtube has a seat machined into it which the bearings rest against so the deeper cups won't work. They also claim that this kind of conversion would almost certainly crack the headtube due to the increased stress of the extra 12mm of stack height. I find the claim that it would definitely crack the headtube pretty dubious, but if there is a seat machined into the headtube that makes only the first 10mm of the headtube 44mm then it definitely won't work. What I really want to know is what is the inside of the '09 Trance like? It it 44mm through and through or is it machined to 44mm for only enough to fit the bearings in?