Thank you everyone for trying to help out. The only real way to know is measure them accurately with calipers as well biked mentioned. I keep reading that Cinelli was 26.4 only back then. That is the problem until they are measured! holiday76 - if you are interested in my 100mm it has some insertion marks at the point where the stem is inserted in the accompanying image and a few scratches, see the photo if it helps. And old's cool, keep me informed on your 70mm and whether the dimensions will allow me to use it with my 3ttt bars, I am interested!