|22.2 mm||7/8"||22.2 mm||7/8"||Steel bars. Mainly BMX, older Mountain bike bars.|
|23.8 mm||15/16"||22.2 mm||7/8"||Obsolete British size for steel handlebars, common on older 3-speeds.
This size was also used for older British steel drop bars.
|25 mm||23.5 mm||Obsolete French size.|
|25.4 mm||1"||22.2 mm||7/8"||Standard I.S.O. size, used on the vast majority of newer bicycles with upright handlebars.
This size was formerly common for steel drop bars.
|25.4 mm||1"||23.8 mm||15/16"||Standard I.S.O. size, used on most bicycles with drop handlebars.
Also used on older British aluminium upright handlebars.
|25.8 mm||23.8 mm||15/16"||Unofficial in-between size used by some Italian handlebar makers for handlebars designed to be usable in either ISO (25.4) or Italian (26.0) size stems.|
|26.0 mm||23.8 mm||15/16"||Italian standard for drop bars, other bars made to fit Italian stems and some high-end aftermarket drop bars.
This is sometimes incorrectly called "road" size.
|26.4 mm||23.8 mm||15/16"||Older Cinelli and Cinelli copies. Cinelli changed over to 26.0 mm in 1998.|
|27 mm||23.8 mm||15/16"||Titan (obsolete).|
|31.8 mm||1 1/4"||23.8 mm||15/16"||Road oversized.|
Last Updated: by Harriet Fell