Tested: CushCore XC Tire Inserts

Growing up mountain biking with a bunch of boys in the ’90s, it wasn’t uncommon for our group to experience between five and 10 flats per ride. The 26-inch tubes we crammed into the bottoms of our backpacks were more patches than clean rubber, and almost any rock garden could produce a symphony of hissing snake bites.

The concept of running tires without tubes, at the time, seemed wild—but after we watched every puncture spit sealant then close up like magic, tubeless became the Only Way. Sealant and rims improved steadily, and it’s gotten to the point where the young kids I coach now have never had a flat. And lemme tell ya, it’s not because they ride less recklessly. Tubeless works, and it generally works really well. But does it work on everything?

For some, those hissing snake bite haven’t gone away, regardless of the advancements in tubeless technology. That’s why CushCore has gained  popularity among riders who tend to shear off side knobs and crack rims (i.e. the full-face crowd). They tend to be the most abusive and least weight-conscious members of our sport. But what about those of us on the other end of the spectrum?  We wondered if the system holds the same advantages under lighter, more XC-oriented use. 

Installation

CushCore is notoriously difficult to install, to the point that the instructions plead with you to “try our way!!” before getting covered in sealant and breaking all your tire irons. I was nervous, but to CushCore’s credit, I simply tried their way, and it worked out just fine. Maybe it's because the XC inserts are lighter and smaller than the Pro, but I had a far easier time than fellow Bike Mag tester, Jon Weber had when testing the original version.

The challenge is that the foam insert is designed to fit snugly inside the trench of the rim, with a bit of overhang on both sides. That extra material will support the sidewall of the tire once installed, but it makes it difficult to wedge one full bead into the rim, let alone both—and it’s especially bad if the tire is new and sticky, or has a really stiff casing. 

Spraying the inside and outside of the tire with soapy water (part of what CushCore meant as "our way”) helped decrease the friction enough to get everything arranged properly. I was eventually able to seat a set of WTB Rangers using only a floor pump—but I have to add that my arms and wrists were super sore the whole next day.

Here’s the weird thing—I happened to be installing another set of the same tires without CushCore right afterwards, and after my first ride back on the traditional setup, it’s like years of good experiences running tubeless had never happened. Once I’d felt how solid and supportive the set with the CushCore could be, I suddenly found it impossible to believe that anyone actually runs tires full of just air. It made me wonder if we’ll see the same sort of revolution with CushCore that we once saw away from tubes. 

Cost/Benefit

It is a wonderful feeling to roll out the door knowing that you’re basically impervious to flats. I felt more confident in corners, happier crawling over root balls, and totally free to choose any line in chunky descents. As far as improving ride quality and providing flat protection, I agree with the enduro world’s conclusion that CushCore opens up a lot of possibilities. 

However, the 29er XC version of the CushCore system I tried weighs 150 grams per wheel, or well over half a pound for the set. While they’ve clearly made every effort to save weight (by scooping out spaces inside the rim and reducing overall volume) that is not a negligible difference, especially when you consider that it’s in the rotational weight of the wheel. 

The weight translated in some predictable ways; the roll up to speed was noticeably slower, and my usually-quite-whippy-feeling XC rig took on a more subdued feel—not exactly what you want when you’re smashing your brains out up a technical climb. While you might gain some time advantages in cornering or flat protection, I don’t think they’d quite justify the weight in any 90-minute racing scenario. 

Peace of Mind

For daily riding or especially gnarly multi-day races, it might be a different story. Tires and rims take a beating in the real world. If that half-pound saves you changing a flat in the rain or gives you a little extra traction through your nemesis rock roll, then I’m all for it. 

A perfect example would be the eight days I just spent bikepacking the Colorado Trail from Denver to Durango. Running CushCore XC helped me avoid over-inflating my tires to compensate for the added gear weight, and I could actually enjoy the remote, technical trails without fear of pinching a tire. The insert also helps push the bead against the rim to mitigate burping which, again, is a factor when your bike is super loaded up. All said, that extra half-pound felt like a pretty low price to pay for the peace of mind. 

The XC, Pro and Plus options from CushCore are at cushcore.com