Some time about ten years ago most of the Omniums and Stage races I did started doing away with TT bikes for some reason. Except for cat 1/2. I think it had to do with some juniors showing up with $6k TT bikes and winning. I used to be good a TT and won several while catting up and I always used clip on bars. I finally got a TT bike one day and I NEVER won a TT on that bike and in fact went back to my clip ons. The reason why is becasue I rarely trained on the TT bike and thought that it was some sort of miracle bike that would give me an extra 50 watts of streamlined power or something. With clipons you get to ride the bike you are used to riding using your regularly trained road racing muscle groups. Get on a TT bike without training and you just put yourself at a disadvantage. That's the way I see it anyway.