I tried some searching but somehow have not found the answer. I would like to change the Cinelli 1A 100mm stem ( with the older oval logo ) for a 70mm. There are two on ebay at the moment but I am not sure about diameters. The bike is a late '70's Italian make. The handlebars are 3ttt. Are they 26.4 or 26mm clamp size? I cannot accurately measure the difference. Also, is the insertion diameter 1"? One stem is 22.2mm. Thank you for any assistance.