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Every once in a while on the internet this little video comes across whatever social media platform I happen to be wasting time on. It shows an airless tire, made from a waffle-like, grid construction mounted on a Humvee and it’s rolling over a curb to show the compression and traction of the tire. The advantage? No flat tires.
And though it may in theory solve one issue, it creates a handful of others. How many wheel-tires do you have to take with you for long-range drives, soft or muddy conditions and transporting additional cargo?
While the traditional rubber, inflatable tire may suffer flats and create tons of waste every year, there’s no getting around the fact that tires need to be tuneable by air, whether on a truck or a bicycle.
Despite all the innovation that has happened in the mountain bike industry, especially in the last 10-15 years, there is one problem that still has no perfect solution: flat tires and damaged rims, though the frequency of flat tires, at least according to my own experience, has gone way down with the advent of tubeless systems, and wider and shallower rim construction.
But this is the bike industry after all, and there is no such thing as under-innovation. The closest promise came in the mid to late 2010s with the tire insert, and like anything produced in this industry, it came with a heavy dose of marketing.
In 2019 I tried tire inserts for the first time, with the CushCore XC models and I like to think my judgement was pretty square back then as my opinion hasn’t really changed.
“I don’t need much more protection than a few extra PSI, or a heavier tire casing. I could see myself using one of the XC inserts on occasion though, in the rear tire of an enduro bike.”
I’ve never been a full convert to tire inserts but I understand why some people use them. And though I’ve buried the lede horribly, what pains me the most about them is when riders spend thousands of dollars on a boutique carbon wheelset, because they are lighter, more responsive, trail-damping, and less prone to pinch flats, only to wrap them in a tire insert and downhill casing which completely changes the characteristics that make the wheels what they are.
I went on a press camp one year and tested a set of wheels over the course of a few days, took them home, only to find that the all-mountain wheels were installed with inserts, front and rear, under the downhill casing tires.
Gosh, I thought. I knew the bike felt a little heavy, but this explains a lot. What did it all weigh? I had to know.
Looking at the weight of an average tire insert, they range from 150g-250g, or 5oz to 8oz–a quarter- to a half-pound. That alone is not a terribly big increase in weight. It’s close to the penalty some might pay for a dual-ply downhill casing over a trail-rated tire.
The weight for this particular tire with a downhill casing was 1,200g, or 42oz, or 2.6lbs. So in the rear, on top of this burly rim was an extra 3.5lbs of mass, spinning around and around.
The DH tire and insert combo also explained that a wheel brand, which was quite confident in its product, went to extra lengths to reduce the chance of failures on the trip by any means necessary. Things happen, even with a good tire, and even with an insert.
I don’t test a lot of wheels; maybe two to three sets a year. And these tests come at the expense of the brand (and our time) as they’re willing to send these to us free of charge.
There’s already a lot to listen to when reviewing a new wheelset. How vertically compliant does it feel on the trail, or how does that wheel translate small rocks and roots from the ground into the bike? How responsive is the wheel laterally? Does it respond noticeably quicker or slower around corners than another wheelset?
And though again these wheelsets aren’t coming from my wallet, I’d still rather not break them. It’s time consuming enough to swap out a perfectly good wheel set and tires to test another.
Still, I’d be misguided to put a tire insert inside the wheel and have the changed feel in vertical compliance, cornering, and responsiveness to pedaling input and relay that to readers instead of the true feel of the wheel. As I wrote in one review last year, it’s already difficult enough to communicate the nuances of ride feel in a wheel review.
If you talk to tire, wheel, and insert companies, they’ll all have something different to say and the answer is most likely one that supports their own product development. You can’t blame them, and obviously plenty of tire inserts are still being marketed, so there must be enough demand for them.
But if you caught the latest Singletracks podcast, a representative from Reserve says that the majority of folks they interact with don’t seem to use inserts, even their downhill World Cup race team. Reportedly, even Greg Minaar didn’t like how they affected the feel of the wheel. Not to mention, for consumers they are still a stressful install.
“It’s hard to get super excited and motivated about sticking this big, heavy thing inside your wheel unless there’s a real need at this point,” said Joel Smith of Reserve in the episode.
But theoretically, the more money you spend, the better the wheel should perform, and give you the desired characteristics. There’s no getting around the fact that we need tires to ride, but if it takes a big block of foam inside to reassure us that they’ll be safe, maybe it’s worth pursuing a less expensive set of carbon wheels, or aluminum, which are more forgiving during harsh impacts.
Carbon wheels earned a reputation for being lighter than aluminum wheels, but lately it seems less and less of the case. It could be that to make carbon wheels more durable, more material had to be applied increasing the weight.
Weight differences between the two are now almost too small to justify the $1,000 difference on some top-end wheelsets. Where carbon rims gain an advantage is that they may require less maintenance and truing over time, but does it matter if you have to ride with the risk of a cracked wheel in the back of your head all the time, insert or not?
I can only decide this one for myself, but I know that spending thousands of dollars on one of the most effective bike upgrades out there, only to worsen their handling just feels backwards.
