Review: Box Components “X” 35mm Carbon Handlebar

Reviewing the Box Components 35mm carbon handlebar and alloy stem.


The Box Components “X” 35mm carbon handlebars are designed to lightweight, stiff, and strong as hell.  Here’s what I’ve found after testing these bars for hundreds of miles.

Box offers the “X” 35mm handlebars in several configurations: from the 700mm no-rise XC version up to the 800mm, 30mm riser DH bar. I tested the Goldilocks “trail” version that’s 760mm wide with 15mm rise, 7° backsweep, and 5° upsweep. Actually, this version is just one step up the aggressiveness scale from the XC bar as Box offers a wider, 780mm trail version with 30mm of rise and more backsweep. Suffice it to say, if you’re an aggressive XC rider or a even a trail rider who spends a fair amount of time climbing, the 760mm version should be a good choice.


As the name implies, the “X” bars are made from carbon fiber, and Box points out the layout is “100% unidirectional,” which allows designers to align loads along the axis of the carbon strands. In another nod toward increasing strength, Box designed the “X” bars around a 35mm clamping area, which means snapping these bars at the stem is even less likely compared to smaller diameter carbon bars.

On the flip side, all this strength leads to increased rigidity, which some riders describe as harsh. Generally carbon bar designs can be tuned to some degree to produce a less harsh ride than a similar aluminum design. In my tests I found the “X” 35mm carbon bars produced a similar ride quality to a typical aluminum bar; no more (or less) harsh on the trail.


Box further differentiates the “X” carbon bars with a uniquely-shaped profile in the transition between the grip and clamping area. Clearly this has something to do with improving strength and perhaps is even a design nod to the company’s box/hex design aesthetic. On the practical side of things I found the profile to make mounting accessories like lights slightly challenging since most handlebar mounts are designed for round bars. Ultimately I was able to mount lights and even an action camera to the shaped area on the bar, though my VIRB camera did work itself loose on a couple of particularly jarring descents.

The 760mm “X” I tested include 10mm cut marks down to 690mm, allowing riders to get the bar width they’re looking for. Personally, I’ve been slow on the uptake with wide bars and would normally chop 760s down to something closer to 720mm. However, when paired with the 65mm Cusp stem I found the wide bars really work well and provide excellent control. If you’re considering purchasing these bars at 760mm or wider I highly recommend going with a stem 65mm or shorter to make up for the added width over a more XC-oriented bar.


As far as geometry goes, determining the right amount of up and backsweep is a personal decision. I can say that 7° back and 5° up works really well for me and is comfortable for 20+ miles in the saddle. The finish on the bars is pretty understated–most will have to look closely to realize that these bars are carbon.

With a weight of 180g for the 760mm version I tested, the “X” 35mm is slightly below the average weight you’ll find for a carbon bar this size. Add in the fact that this bar features an oversized clamping area and the 180g is even more impressive. This bar should retail for $139 with the narrower versions going for slightly less and the wider versions going for slightly more.


The “X” 35mm carbon handlebar from Box Components is a strong choice for riders of all stripes, from XC to DH. And when paired with the company’s Cusp stem, these bars really shine!

Thanks to Box Components for providing the “X” 35mm Carbon bars for review.