I don't understand your question. You have a 26mm stem and handlebars that are made for a 26mm stem. They were made to go together. The rest of the bar is almost always smaller than the center. This makes it easier to maneuver it into a stem (around all the curves) without scratching the hell out of it. If it makes you feel more confident, I have a Nitto Technomic stem with 26mm head and the Nitto M186 bars. Everything fit together perfectly.