I put them on last night actually. Apparently (according to Sheldon) 25.8 is a size used by some Italian manufacturers to allow the bars to be installed in either a 26.0 or a 25.4 clamp, presumably without shimming. Mine are in what I think is a 26.0 and seem fine. You can't buy 25.8mm clamp stems very easily I found.
I can measure the drops when I get home for you hugo.
I put them on last night actually. Apparently (according to Sheldon) 25.8 is a size used by some Italian manufacturers to allow the bars to be installed in either a 26.0 or a 25.4 clamp, presumably without shimming. Mine are in what I think is a 26.0 and seem fine. You can't buy 25.8mm clamp stems very easily I found.
I can measure the drops when I get home for you hugo.