I'm based in the UK and have bought some new handlebars that are 31.8mm for a hybrid 8 gear bike.

My old handlebars were smaller in diameter so my old gear shifter won't fit. No gear shifters online actually say the diameter of the handlebars they're made for. Is there a standard diameter for mountain bikes and road bikes? Can someone link me to an example 8 gear shifter that will fit 31.8mm handlebar?

Any help really appreciated.

  • Closely related but it's old and unresolved, and it discusses the brakes as well. Are your brakes sorted? How?
    – Chris H
    Jun 15, 2018 at 15:54

2 Answers 2


22.2 mm (7⁄8 in) is the standard diameter for the brake, shifter and grip area of MTB handlebars.

I think you bought a bar that was designed for bar-end shifters only. Easiest way out of this is to swap the bar for one that allows shifters and brakes to be mounted on the area between the stem and forward turn.


Your handle bar is only 31.8mm thick at the clamping point. The parts of the handlebar where you mount the shifters/brakes/grips are 22,2mm ( I think ). Therefore they are always the same and you can mount your old or just buy one that is compatible with your deraileur.

  • It's a bullhorn handlebar though and it's 31.8mm up to the turn. I'd really like to mount the shifters near the clamping point. :/
    – Lottie
    Jun 15, 2018 at 8:09
  • Ah ok, then you should have a look at bar end shifters
    – nollak
    Jun 15, 2018 at 9:58
  • @nollak But bar-end shifters are at the ends of the bars, the place farthest from the clamping point. Aug 14, 2018 at 15:34
  • Yeah but to my knowledge there are no shifter clamps available to mount on 31,8mm diameters. In case of bullhorn handlebars bar end shifters are mostly used. So there is either the possibility to run bar end shifters, run single speed or use another handlebar
    – nollak
    Aug 15, 2018 at 8:03

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