I’ve always been wary of unsecured cargo. A cautionary story I once read stuck with me and now I won’t drive with loose gear in the back. After an extended bike trip with my SUV packed to the roofline, I decided a rooftop cargo box was necessary.
I picked the Yakima CBX18 (about $1,099). The 18 denotes cubic feet; it’s the second-largest box in Yakima’s line. On my first outing it held two giant camp chairs, firewood, two sleeping bags, a four-inch Exped sleeping mat, water, shovel, axe, my bike duffel, kitchen kit, and more. I left food and a cooler inside only when the cooler was strapped down.
Why this box? I’ve owned both Thule and Yakima before and chose the CBX18 for four reasons: it’s easy to attach to crossbars, it opens from either side, it has a reasonably sleek profile for the capacity, and I was satisfied with my previous Yakima box.
Mounting is straightforward. The CBX uses four curved clamps that ride in tracks underneath. With a dedicated four-sided tool you open the clamps, position the box on the crossbars, slide the clamps under the bars, and tighten. A torque stop helps avoid over-tightening. Whether solo or with help the install took about 15 minutes. The empty box weighs roughly 65 pounds; I lifted it onto the roof by draping a moving blanket over the tailgate and sliding the box up at an angle.
What I like: bi‑side access is genuinely useful with a 38‑inch-wide box, especially when reaching heavy items on the far side. Yakima’s single-key system is convenient. The box’s 17‑inch height gives a good volume-to-profile ratio for many vehicles.
What’s annoying: the plastic shell is about 91 inches long and can flex, which makes the fore and aft latches a bit fussy. I found the best way to close it reliably is to bring the lid down gently at the center, then press the front and back edges over the latches until they click.
Expect a fuel penalty. On my Lexus GX470 highway economy fell from roughly 20 mpg to about 18.5 mpg with the box mounted.
Bottom line: the Yakima CBX18 is a solid, practical choice if you need significant roof storage. It’s not the only good option—Thule and other brands make competitive boxes—so choose based on how you’ll use it (left on year-round or only seasonally), vehicle and garage clearance, and capacity needs rather than loyalty to any one brand.