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This post compares the advantages and disadvantages of 31.8mm and 35mm handlebars.

The Advantages of 31.8mm Handlebars

• Availability

31.8mm bars are still the current MTB standard. For that reason, customers have access to a larger number of brands and models. You can find a 31.8mm bar at pretty much every bike shop.

• Lower Price

The greater supply results in lower prices. It’s not difficult to discover relatively inexpensive 31.8mm aluminum handlebars of good quality.

• More Compliant

31.8mm handlebars are more compliant and thus reduce some of the vibrations reaching the rider’s joints.

The Advantages of 35mm Bars

• More “clamping” area

35mm bars offer approximately 10% more clamping area. Consequently, the stem needs less torque to efficiently grab the bars. This is beneficial to carbon handlebars because the material is not very resistant to clamping/squeezing force.

• Extra Stiffness

Some 35mm bars are incredibly stiff to the point where some people complain of too much wrist stress.

Nonetheless, stiffness has a positive side too – it increases the bike’s responsiveness.

• Potentially Lighter

Large diameter tubing has a wider structure and thus needs less material to match the strength of small diameter tubing.

A thick tube made of tough material could still be weaker than another one that has a bigger diameter.

The same applies to handlebars. For that reason, 35mm bars can have thinner walls while still offering the strength of 31.8mm models. Hence why 35mm bars are often lighter.

• Potentially Better For Heavier Riders

Some people say that 35mm bars can be better for heavier riders due to the extra size and thus strength.

In practice, however, 31.8mm can be brutally strong too. For example, there are extra-thick downhill bars that would require a sumo wrestler to crack.

The Downsides Of 35mm Bars

• Too Stiff

The main weakness of 35mm bars is that many models are just too stiff and thus harsh on the rider’s connective tissues. Consequently, many people switch back to 31.8mm after experimenting with 35mm models.

• Fewer Choices

35mm handlebars are not as popular as 31.8mm and subsequently, there are fewer models available on the market.

• More Expensive On Average

35mm bars are part of a smaller niche that only dedicated riders are interested in.

Subsequently, 35mm bars are considered somewhat of a premium product and come with a higher price tag.

That said, the final price depends on the brand and the model. Some 31.8mm bars are quite expensive too.

Note: You will also have to add a new stem to the bill because 31.8mm models are not designed to accommodate a 35mm bar.

Some people file their stems or add longer bolts to make the combination possible, but that way you’re weakening the stem which is an integral cockpit component whose failure results in spectacular crashes.

Also, the procedure will void the warranty of the stem and the bars.

Weight Comparison

The table below compares the weight of 31.8mm and 35mm handlebars:

Material: Aluminum

Conclusion: On average, the aluminum 35mm bars in the table above are 6.6% lighter.

Material: Carbon

Conclusion: On average, the carbon 35mm bars in the table above are 3.9% lighter.

Ultimately, the weight savings offered by 35mm bars are not substantial enough to make a difference, unless you’re trying to build the lightest possible bicycle.

Variations Between Brands and Models

It’s also worth mentioning that there are many model variations.

In some cases, a 31.8mm bar will be stiffer than a 35mm one due to the used material and engineering.

For that reason, it’s recommended to check the reviews of the bars that you’re analyzing or ask the company directly to gain more insight into the bar’s performance.

FAQ: Is an upgrade from a 31.8mm to 35mm bar worth it?

The switch from a 31.8mm to a 35mm bar is not exactly an upgrade because it does not result in a clear performance advantage. The main reason to switch is to get a stiffer bar.

And since not everybody likes the feel of ultra-stiff bars, the transition is hardly an upgrade.

Truth be told, many people consider 35mm bars “another unnecessary standard” in the biking industry that exists simply for existing.

Summary: What You Need To Know

The main pros of 35mm bars are that they’re extra stiff and about 5% lighter. However, they offer a harsh ride and have small to no advantages over a quality 31.8mm bar.

The transition from 31.8mm bars to 35mm cannot be called an upgrade when both models have similar architectural characteristics (length, construction material…etc.)