Schwalbe Thunder Burt Tires Can Turn Hardtails into Gravel Bikes [Review]

You can call Larch trees by the name Tamarack in some parts of the world, and you can also call some hardtails “gravel bikes” if you happen to pedal them on dirt roads. Super fast-rolling XC race tires like the Schwalbe Thunder Burt will help convert almost any hardtail to a passable gravel bike, keeping the “N+1” sum lower and saving cash. Sure, the gearing won’t be ideal for gravel racing, but if your aim is to have an endurance machine in your fleet there’s a good chance your hardtail can pull dual duty.

I decided to test the 29×2.35″ version of these tires to give them a small amount of extra cushion, but they also come in. a 2.1″ width if speed and weight are your deciding variables. At 621g these are the lightest “XC tires” I’ve ridden in many years. Cut to about half the weight of my favorite Schwalbe tread, I wouldn’t buy a set of these for riding singletrack unless I lived somewhere like Bend, Oregon with mostly smooth flow trails. Otherwise, I’d call the Thunder Burt a dirt-road tire. I have a good buddy who lives in Bend, riding and racing XC on this tread regularly, so it is possible. It’s also not my jam.

Wherever you may roam, the important element of these tires is their subterranean rolling resistance. They’re hella fast. So fast, in fact, that my bike felt propelled by an electric motor when I first swapped them. The Schwalbe Thunder Burts and carbon Whiskey fork laughed allowed at my former 130mm gravity-ish setup while we strode away over small stones. Tight and shallow center tread like this rolls so well that I don’t mind going on regular pavement rides with this setup. There’s no squirm from the tiny blocks, and it’s rather difficult to lean the bike over enough to reach those slightly taller shoulder lugs, leaving the tire to roll efficiently and comfortably at flat-asphalt speeds.

A balloon-animal-round shape to this tire keeps most of it off the ground, minimizing the traction patch for speed. That smaller contact also means less grip, and it’s just the right amount for some fun drifting on hardpacked dirt or gravel. While it is possible to lean the bike into those dainty shoulder lugs, it’s a fair bit of effort for a moderate return. When I’m riding fast enough to properly tip the tire and engage those lugs the speed is often enough to also let it drift a bit. On dry hardpack this might be a different grip narrative, but over PNW dirt roads during the winter months, this tire is a festive drifter. It breaks loose about as predictably as you would expect for a file-tread, and the sideways slide has been the best part of dirt road riding so far.

Much of the Thunder Burt tread connection is related to the wind inside. Tire pressure always has a large effect on grip and without suspension this variable gains significance. I run 25psi rear and 20psi up front for a cozy balance between puncture protection and grip. I could go lower, but the local dirt roads have rather chunky bedrock and I’d rather keep the tube strapped to my frame. Furthermore, the thin Schwalbe Super Race casings are far more supple than most of the tires I like, and a skosch more air pressure helps those sidewalls stand up somewhere slightly closer to the support and rebound character that I like in a tire. That same suppleness makes for a well-damped ride, with a good amount of gravel vibration consumed by the tire itself.

Braking traction with this tire is laughable, as it should be when the tread is solely speed-focused. On super hard dirt that’s basically concrete, it will grab ahold and slow quickly. Over any looser conditions, those little baby teeth take their time to scrub speed. I don’t often find myself needing to slow abruptly on dirt roads or buff singletracks, and the amount of braking ability Thunder Burt abides seems appropriate.

Preventing punctures with the Burt is a matter of air pressure and line choice more than one of casing characteristics. These tires are designed around speed and efficiency, so if you hit something sharp they won’t have your back like a heavier carcass.

Conclusion

Given both their rolling resistance and feathery casing these tires remind me of the Kenda Small Block Eight rubber I used to run on the rear of my XC race ride. The Kenda was a hair heavier and slower, but the intention was roughly the same. Make a tire that goes as fast as possible with the lowest watt output. For dirt roads and billiard-smooth singletrack, I’d say Schwalbe nailed it with the Thunder Burt. Fun-Dirt-Burt?