When it comes to protecting your rim from damage while running low tyre pressures, CushCore is one of the best-known options on the market. To see just how tough it is, we got our local rim-dinger, David Hayward, to put them through the grinder as part of a tubeless insert group test. Over to David!
CushCore arrives as a very tidy box set, with two inserts contorted into it, along with a pair of special valves, instructions, and a whole bunch of rim stickers just in case you’re feeling the Brand Loyalty… or perhaps are the kind of person who’d forget which wheels you put them in.
The first thing that hit me about them was the very chemical smell, which has faded away over the months I’ve been using them. The second thing that stuck out was that CushCore inserts are moulded as a continuous closed band, so no need to mess around with Velcro or zip ties.
They’re made for specific wheel sizes, and available for 26in, 27.5in or 29in wheels. At the sides, there are v-shaped grooves every so often to let sealant pass though.
The third thing that stuck out was the on-brand set of green valves, very long and with unusual bases. This is because the inserts hug the rim bed so tightly that with a standard valve, they’d prevent flow of air or sealant into the tyre. CushCore’s valves have raised bases with holes in the sides, allowing fluid and gas to pass. If you don’t like green, they also sell valve sets in red or black. As well as boxed sets, you can buy single inserts too, and they come in two different widths for standard and plus tyres.
The ones we’ve been testing are standard width ones, which weigh in at 250g per wheel.
Fitting CushCore is slightly awkward, and requires just enough ingenuity you might end up frustrated if trying to work it out from scratch. Thankfully, there’s the internet, with several good how to videos out there. As well as printed instructions, CushCore even place an obvious sticker inside the box pointing you to an online tutorial.
The instructions are excellent, and make installing it relatively easy. Among the good tricks are using a tyre lever to stuff the tyre bead downward, creating more slack, and using a hammer underfoot to hold the rim down while you stretch the insert on. It’s all a bit awkward to express verbally, so I’d suggest watching it if you’re curious:
Like the Vittoria Air-Liner, I found CushCore to be impossible to fit with Panaracer’s Pandura tyres due to their oddly textured inner walls, but CushCore worked just fine with an assortment of Vee, Onza and Maxxis tyres.
Coupled with its tightness, the insert profile really does a good job of pushing tyre beads down onto the rim, and that makes it one of the more difficult inserts to fit. But take your time and follow their method, and you’ll get there just fine.
CushCore’s shape leaves quite a large remaining air volume inside the tyre, giving you a lot of scope to try out different pressures. I’ve generally settled on running 17psi inside a variety of 27.5in tyres around 2.3-2.4in wide. In this respect, it’s certainly more versatile than Vittoria’s Air-Liner, similar to Schwalbe’s Procore, and locks beads down unlike floating inserts such as Huck Norris.
The tradeoff for this compared to the Air-Liner, is that CushCore puts less foam over the oh-so-vulnerable edges of the rim. That’s not to say it’s unprotected; it’s much more rim protection than standard tubeless, and the amount of material over there is thicker than floating inserts like Huck Norris. More than just rim protection though, it’s biased toward locking beads down and allowing air pressure tuning.
That means if you’re the kind of rider who regularly rolls tyres over, this would work well for you. If you straight line everything though, you might be better off looking at ProCore or Air-Liners for the greater protection they can provide. Bear in mind though, ProCore is likely to void carbon rim warranties, because the inner tyre runs at higher pressures than most carbon rims are designed for. CushCore will achieve the same bead locking without applying 60psi to a rim not designed for it.
So then, this is more for people who roll tyres off rims than those who smash wheels, and as a light but occasionally clumsy rider, I’m the latter. For some people, CushCore will have the perfect balance, but not me. The carbon rim. I smash it. There’s a hole in my CushCore now, too.
To be fair, it was a very big, very fast, very silly smash. I’ve flat spotted rims through ProCore and Huck Norris before, and I’m pretty certain neither would have saved a rim from this impact. It’s not the CushCore’s fault.
I am gonna miss that Mavic XA Pro wheel though. It was beautiful. I’ll confess, in the moment I may even have resorted to strong language, sinking to my knees and gently whispering “dang it all to heck“.
Out there on the trail, I couldn’t get the tyre off or the CushCore out, so got to roll the mile or so home testing out its run-flat capabilities. I was impressed by this; despite no air in the tyre, it still had a lot of stability and cushioning. Normally, if you stubbornly roll onward on a puncture, you can feel loads of tiny impacts steadily eroding your rim and tyre. On CushCore, it just felt like a very squishy tyre, but still controllable and with traction.
This was a bit more traumatic than other inserts I’ve been testing. CushCore *really* pushes down on those tyre beads, no matter if there’s air in the tyre or not. Rolling home on a flat can’t have helped either. As well as destroying a carbon rim, I’d also smashed a bloody great hole in the tyre, well beyond repairable, so rather than continue wrestling, I ended up just cutting the tread off then yanking the beads out with pliers.
Dismantling it like this revealed just how unlucky I’d been: not only was it a really hard impact, but it hit dead over both the rim bead, and one of the small v-shaped sealant channels where the foam is thinner. The impact also made a lovely hole in the CushCore, big enough that a spot of daylight shines through it now.
Like other foam inserts that err on the thin side to save weight and preserve air volume, CushCore showed a lot of telltale snakebite marks on the upper and lower surfaces. To its credit, I hadn’t heard any of them happen, except that fateful last one.
One thing also worth noting is that there was absolutely zero sealant residue clinging to the CushCore, so it seems quite chemically resistant compared to some other brands of insert.
Don’t let my smashed wheel put you off CushCore. Ultimately I don’t think there’s anything else out there at the moment that’s that compatible with carbon rims and can lock tyre beads down this firmly – it is rock solid, and competitive types will appreciate that dependability.
However, nothing makes a wheel indestructible. If you tend to burp tyres a lot, and want to run lower pressures without that risk, CushCore is probably the rim protection system for you. For Straighty-McStraightline who biffs rims on the regular, maybe something a bit burlier (such as Procore or the Air-Liner) would suit better though, because it’s not going to save you from yourself. At least, not all the time.
|Product:||Inner Tyre Suspension System|
|From:||Ison Distribution, ison-distribution.com|
|Price:||£79.99 (per wheel)|
|Tested:||by David Hayward for 2 months|