Besides the obvious, size, why do I care? It seems most road bikes have 1 1/8 and more tri bikes have 1" head sets, I have hard time believing a 1 headset would be that much more aero? I think I heard 1 1/8 came from mountain bikes? Just cheaper for bike companies that make both? What gives?
Kind of a quandry. At its core I believe (IMHO) the move to 1&1/8" headsets was to put the entire road and MTB world on the same standard. makes good economic sense. On the other hand, john Cobb and Gerard both know that a 1" headtube/steertube is a good bit more aero than 1&1/8" The big problem is with aerobars like Visiontech, which only recently became available in 1&1/8". Basically, it represents an inconvenience. If I had my druthers, everything on the road would be 1" and the dirt stuff would be 1&1/8"
…and so what were the folks at Klien thinking with that inch and a quarter? Certainly the headsets are cheap on Ebay when you can find them.