Premise: Bikes equippes with one handlebar (naked, sport touring, etc), use handlebar with 22 or 29 mm section in the middle, and 22mm section in the end part (where grips are located).

Custom as H-D use 1 inch handlebars, sports bike use two handlebars.

A 22 mm handlebar looks smaller than a 29 mm handlebar, just watch the mid section.