"any only normal handlebar" is a very vauge description. Racing handlebars on vintage light weights are usually from europe and as such their size differs even within the same country. A lot of japanese bikes used 25.4mm and indeed Nitto still makes them today. If you walk into a bike shop today you have two choices. 26.0 or 31.8 for road bars with the exception of course of some nitto (which in Canada you can order through almost any LBS).