We’ve designed this mount to fit all the most common handlebar sizes. The bracket on the mount is 35.6mm in diameter, and it comes with spacers which are 31.8, 25.4 and 22.2mm. These should fit all the most common handlebar sizes. If you’re having trouble with the fit, check that the spacer you’re using is the same size as your handlebars - the spacers are labeled - and we recommend avoiding putting the mount on any tape as this can add extra thickness.