For decades, various manufacturers have dabbled in flat-proof bicycle tires that have a solid or foam-filled core. The problem is, those tires tend to be heavy, plus there's no way of adjusting their firmness. Italian startup MrWolf is now offering an alternative, in the form of the Banger. Not only is it lighter and more adjustable than a solid tire, but it reportedly also gives mountain bikers a smoother ride than they'd get with regular tires.

Designed specifically for mountain bikes and e-bikes, the Banger is a loop of "technopolymer" (i.e: a proprietary low-density foam) that sits inside a regular third-party tubeless tire. Once installed, it occupies 95 percent of the tire's inner volume, which would otherwise be filled with air. That does still leave some room for air, however, so it remains possible to adjust the hardness according to rider weight, trail conditions, or other factors.
Additionally, the polymer is claimed to have a damping effect when riding over obstacles. This means that whereas a purely air-filled tire may bounce off a rock, for instance, a Banger-filled tire is more likely to just deform around it and "soak it up." As a result, riders should experience less bumps, along with increased traction.
Punctures are said to be much less likely to occur, although if they do, the rider can keep going on the Banger alone, without any air in the tire. And yes, sealant can still be used.
MrWolf additionally claims that the insert should guard against pinch flats and "burping" (wherein a big hit causes a tubeless tire to pop off of the rim), plus it will help keep the tire seated when taking hard corners.
There is a bit of a weight penalty, though, as compared to just using plain ol' air. Each Banger weighs anywhere from 180 g (0.39 lb) to 350 g (0.77 lb), depending on the size – it's being made for 26, 27.5 and 29-inch tires, in a variety of widths.
If you're interested in getting some, the Banger is currently the subject of a Kickstarter campaign. A pledge of €149 (about US$162) will get you a set of two, when and if they reach production. The planned retail price for a set is €250 ($272).
Prospective buyers might also want to check out Schwalbe's sort-of-similarProcore system.
Source: Kickstarter