Bicycles are hilarious because the same sizes will be designated in inches or millimeters depending on where or why they are taken. E.g. handlebars are 31.8 mm or 25.4 mm (1¼" and 1") but steerers are 1" or 1⅛". Wheels of the same diameter will be called 28", 29" or 700 (and the diameter is actually 25½" but it's only called "622 mm"). And even when they use metric from the start for something that is not a standard fastener already they end up with things like 28.99 mm spindles (not to be confused with 30 mm spindles, which also exist).