A Comprehensive Guide to Bike Handlebar Sizes

Posted on Jun 5, 2013 in News | 0 comments

A Comprehensive Guide to Bike Handlebar Sizes

Few bicycle components are as integral to the comfort of your ride as handlebars and for this reason, they’re often one of the first parts to be replaced when cyclists decide to customize their bikes. But with such a daunting array of different diameters, widths, drops, and rises how do you know what’s the right choice for you? When sizing your new handlebars, there are two important parameters to consider: diameter and width.


The first consideration should be to make sure the diameter of the ‘bulge’ (the slightly thicker part at the middle of the bars) is compatible with your stem clamp. Handlebars can be separated into four rough categories, each with a specific set of common clamp sizes:

  • Road Bikes – Road bike handlebars are pretty much always made in the drop style, and generally come in two different clamp sizes – the older 26 mm and the newer ‘oversized’ 31.8 mm.
  • Commuter/Cruiser Bikes – This category includes a significantly wider array of styles including mustache, high-rise, randonneur, and multi-position bars. Clamps sizes vary widely as well, so you’ll have to keep a close eye on them to make sure they’re compatible with your stem clamp.

For these bars, not only will you need to keep in mind the bulge diameter, but also the diameter of the grip area of the bar. Shifter and brake clamps for mountain bikes are designed to fit around a 22.2 mm diameter, while road bike shifter and brake clamps are designed to fit around a 23.8 mm diameter. It’s crucial to ensure that your bars fit both your stem clamp and your brake and shifter clamps.

  • Mountain Bikes – Mountain bike handlebars are usually either flat or riser bars and also usually come in two different clamp sizes – the older 25.4 mm and the newer ‘oversized’ 31.8 mm.
  • BMX Bikes – This is the most straightforward category when it comes to diameter, because BMX bars have no bulge. They also only come in one style (a mid/high-rise with a cross-brace for extra strength). Both the stem clamp and grip area diameter on these bars will always be 22.2 mm (7/8”).

(Important note: Though the newer 31.8 mm ‘oversized’ bulge makes many mountain and road bars cross-compatible, you should never try to use a 26 mm bar with a 25.4 mm stem clamp, or vice-versa. Also, this universal bulge diameter does not mean that the grip diameter will be compatible with your brake and shifter clamps).


Next let’s tackle width. The standard approach is that your handlebars should be about as wide as your shoulders, maybe a bit wider. Really though, this should be taken as a suggestion. We’ll separate the bars into the same categories we used to examine diameter:

  • Road Bikes – Drop bars usually vary in width from about 34 cm for the narrowest of bars to 50 cm for bigger riders. The shoulder width rule is most applicable in this category. Some shops will size your road bike bars by putting them over your shoulders like a coat. If your shoulders fit snugly but comfortably within the drops, then you’ve found about the right fit. This method isn’t foolproof, though. Some road-bikers prefer their bars to be slightly narrower than their shoulders, sacrificing comfort in order to enhance aero-dynamicity. Conversely, some cyclists prefer them slightly wider to open the chest, encouraging cooling and easier breathing.
  • Commuter/Cruiser Bikes – Again, this is the category in which we see the widest variance. Width is oftentimes less of a concern for these types of bikes because they’re generally used for shorter rides. The ‘shoulder width’ approach is a good rule of thumb for comfort, but upright style bars for city bikes and comfort models will almost always be wider than shoulder-width. On the other hand, some commuters opt for very narrow bars to enable easy maneuvering through dense auto traffic.
  • Mountain & BMX Bikes – We’ve lumped these two categories together because they generally abide by the same school of thought when it comes to handlebar width. That is, ‘wider is better’ (Some new mountain bike bars are in excess of 75 cm wide). The reason for this is that wider bars increase leverage, lending greater steering control and minimizing influence from trail feedback. This rule does have its exceptions, though. Slow-speed, single-track mountain-bikers will generally opt for a narrower bar to more easily navigate between closely spaced trees.

As with any bike part purchase, when choosing handlebars the most important thing is remember your specific needs. There is no ‘one-size-fits-all’ solution. If you feel like you’re in over your head, there are a variety of cycling forums where you can post your questions and get suggestions from a slew of other cyclists. It’s also never a bad idea to make a trip down to your local bike shop and get some feedback from the experts in person. Safe travels!



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