The courses for Unbound Gravel 2024, the famous race across the Flint Hills of Kansas, were announced today. This year, the race heads north from Emporia, where the gravel is rougher and the hills are steeper and longer than in the south. We’ve asked two of the pro racers who work with us on tire R&D about their advice when choosing tires for Unbound.

Ted King has won Unbound twice, and placed in the top ten every time he’s entered the race. He came to us after having trouble with the (non-Rene Herse) tires he ran. We’ve developed the Endurance and Endurance Plus casings together, based on Ted’s unique experience with the sharp rocks of the Flint Hills.

JH: If there’s anybody I’d ask about tire choice for Unbound, it would be you. You’ve raced on all the different courses—what’s your tire recommendation for this year, with the race going north from Emporia?

Ted: As much as the north course and south course are different at Unbound, in the grand scheme of the type of terra firma on which we’re riding, the two courses are actually very similar. My point being, I would suggest the same tire if I’m going north or south. In all likelihood, I’ll end upon the 44 mm Snoqualmie Pass tires in Endurance Plus casing. There aren’t a lot of dynamic corners, so I feel confident running slicks over the 200 miles. The rocks and gravel of Unbound are renowned for causing flats, so the Endurance Plus casing is a no-brainer for me. It’s a very strong casing and can withstand the punishment of these notorious flint hills. All my runs on the Endurance Plus in Unbound have been trouble-free from the tire perspective.

JH: So you recommend running 44 mm tires?

Ted: Right, the weather is the biggest variable for me. If it’s dry, for sure I’m on the 44 mm Snoqualmies. This is a wide tire that I can run at low pressure for excellent grip and a smooth ride over the rough terrain. I could squeeze in a 48 mm tire on my race bike, but there’s always the risk of mud buildup, even in the smallest puddles, so 44 is the goldilocks fit. We know it can be a wet and filthy year, too. If that’s the case, I’ll bump down to a 38 mm Barlow Pass for that additional tire clearance.

JH: What about knobbies?

Ted: If knobby tires are something that give you more confidence, by all means the Manastash, Hurricane, or Steilacoom are all excellent choices as well! I’ve run knobbies and slicks at Unbound, and just find slicks to be my personal choice. I’ve made this claim before, in 2021 (where I finished 4th). I’m pretty sure I’m the first person to have run slick tires at Unbound. Fast forward to the present, and it’s now quite common!

JH: How do you determine your tire pressure?

Ted: My knee-jerk response is “put in a lot, take out a little.” I’m kidding just a little bit here, but there’s a not-insignificant chance that you’ll get some kicks in the tires over the course of the 200 miles, so losing a few pounds of pressure here and there is a possibility. My more accurate rule of thumb is to use the Rene Herse Tire Pressure Calculator and add an extra pound of pressure front and rear.

JH: You started racing in Unbound in 2016, just after you retired from the pro circuit in Europe. You’ve ridden many different bikes and tires in Unbound—I think the first year you were on a 650B Cannondale with a Lefty suspension fork. If somebody has several bikes, which one should they take to Unbound?

Ted: If you’re blessed with several bikes, then I recommend opting for the one on which you’re most comfortable. Sub-ten hours is a winning time, so knowing you’re setting out on the bike for a dozen hours, maybe twenty hours (!) or more, choosing the bike that inspires the most confidence is my suggestion.

JH: Do you have any special bike setup secrets for Unbound?

Ted: Honestly, no! The race has become so ‘racy’ that a relatively minimal setup is what I suggest, which is my standard rig. I’ll often use a top tube bag for extra storage, especially for the caloric needs. But I don’t double-wrap bars or add any other gizmos to the bike. Similar to the previous question, my Unbound rig is a bike that I ride often. Just using the setup with which I’ve become comfortable is my preference.

JH: Thanks, Ted. That’s solid advice!

Brennan Wertz needs no introduction (above at the finish of the 2022 Unbound). The 2024 season has barely started, and he’s already won the UCI Highlands Gravel Classic, the Sea Otter Classic Gravel Race, and the Huffmaster Hopper—and he’s qualified for the UCI Gravel World Championships in Belgium! As all eyes turn to the upcoming Unbound Gravel in Emporia in the beginning of June, we took some time to chat tires with Brennan.

JH: Unbound Gravel, one of the biggest and most prestigious gravel races in the world, is just around the corner. What are you expecting to encounter on this year’s course to the north of Emporia?

Brennan: My first-ever Unbound Gravel was back in 2021. That year we also raced to the north, and I remember being quite surprised by how rough the surface was. I had heard the rumors, but you still never really know what to expect until you set foot (or tire) in a location. For this year’s race, I’m expecting similarly rough, rowdy, and tire-shredding sharp rocks. I’m also expecting it to be quite hot. The last two years have been cooler and damper. But I know how hot and windy it can be out there in the Flint Hills of Kansas.

JH: How does the gravel in the northern parts of Kansas compare to what you’ve encountered elsewhere?

Brennan: I’ve ridden a lot of pretty rugged gravel terrain, both while traveling and at home in Marin County, California. I love exploring trails that are off the beaten path, which means I often end up in areas where I probably shouldn’t be with a gravel bike. But even with all this experience of riding rough terrain, nothing is quite like the Flint Hills. For sure there are plenty of sections of typical, Midwestern rural gravel roads that are very straightforward—it is 200 miles after all!—but the rough sections are proper and plentiful. The rocks are razor sharp, super chunky, and have a tendency to move underneath you. Where I’ve encountered issues in the past at Unbound is when a large rock moves after a rider directly in front of me hits it, sending it directly into my pathway, resulting in an unavoidable impact. This is a much greater consideration for riders who are riding in close contact with one another, like those of us racing for the win in the pro race, where drafting at high speeds is crucial. For riders who prefer to have a bit more space in front of them and a better line of sight, this is less of an issue.

JH: You’re a tall and ultra-strong rider, which means your tires have to be extra-tough. When you add the sharp rocks of the Flint Hills into the mix, how does that affect your tire choice?

Brennan: Extra tough indeed. I can’t imagine ever starting Unbound without the Endurance Plus casing. When it comes to Unbound, flatting is such a big risk that I take every possible precaution I can to avoid it. I had a catastrophic flat take me out of the front group in 2022, so now I am doing everything in my power to avoid that. For 2024, I am also planning on running inserts in my tires, as well as extra OrangeSeal sealant. I’m still doing a little bit of last-minute testing, but I’m 99% sure I’ll be on the 44 mm Manastash Ridge Endurance Plus for this year’s race. For many other races on the calendar, I find the Endurance casing to offer the perfect balance of speed, grip, and durability. But for Unbound I’m not taking any risks. The fastest tire at Unbound is the one with air in it.

JH: What tires would you recommend to somebody who is a bit lighter and maybe not as strong?

Brennan: To be honest, I would still recommend the Endurance Plus. Again, the fastest tire at Unbound is the one with air in it…

JH: The other piece of the tire puzzle is pressure. What do you recommend?

Brennan: For me personally, I’ll likely run my 44 mm knobbies at around 34/35 psi. I’ve come to this pressure through countless hours of riding and experimenting with different setups in training. Perhaps not coincidentally, that’s also the ‘soft’ value the Rene Herse Tire Pressure Calculator suggests for my weight (92 kg). As far as my recommendation, I would suggest using the Rene Herse Tire Pressure Calculator to find a good starting point and then dial in your personal preferences based on that starting point.

JH: What are your goals for Unbound this year?

Brennan: Like any race I line up for, the goal is to always be fighting for the win in the final. But Unbound is a special race and there are lots of opportunities for things to go wrong. My biggest goal is to calmly, efficiently, and effectively manage the inevitable setbacks and challenges that I will face along the way. I’m confident that if I do that well and have a relatively smooth run, I can be in the front group fighting for the win at the end.

JH: Thank you Brennan, and best of luck in Kansas!

So we have two strong votes for 44 mm tires in the Endurance Plus casing, both from very powerful and tall riders. For perspective, Lauren de Crescenzo (above at the front of the group) has ridden the Endurance casing in Unbound twice with zero problems. She also ran the 44 mm Snoqualmie Pass, and she’s a lot lighter than Ted or Brennan, so she can run lower pressures and thus reduce the risk of tire trouble.

I’m heading to Kansas, too, for another go at the 350-mile Unbound XL. (Above is the 2022 edition.) With the smaller field—meaning I can see the road ahead—and ultra-wide tires—I’ll be running 54s—I’m also confident that the Endurance casing is all I need. And I do need any help I can get from the faster speed of the more supple casings. (I’m even toying with the idea of running Extralights, as I’ve done twice in the equally rough Arkansas High Country Race.)

That’s really the crux of it: The tougher your tires, the more speed you give up. This can be mitigated to a degree by using the best materials: Stronger and thinner threads are harder to cut than soft, thick casings. Another key factor is running wider tires at lower pressures: Lower pressure puts less tension on the casing, making it harder to cut.

Based on all this experience, tire advice for Unbound can be distilled into just a few elements:

  • Pick the bike that’s most comfortable (and fastest) for you.
  • Run the widest tires that fit with sufficient clearance for mud build-up.
  • Choose the Endurance casing if you are looking for the perfect balance of durability and speed. Our Endurance models are among the fastest gravel tires in all tests, yet they are stronger than most other gravel tires thanks to their ultra-high end materials.
  • Use the Endurance Plus if you really want to eliminate the risk of flats. The Endurance Plus is the toughest tire this side of downhill mountain bike tires, yet it retains most of the supple speed for which Rene Herse tires are famous.
  • Use the ‘soft’ value recommended by the Rene Herse Tire Pressure Calculator as a starting point for figuring out your tire pressure.

With all the racers ordering tires, it’ll be a busy few weeks here at Rene Herse Cycles. If you put ‘Unbound Tires’ in the Comments field when you place your order, we’ll move your order to the front of the queue to ensure you get your tires with plenty of time to dial in tire pressure, sealant and everything else. Most of all, good luck in Kansas!

More Information:

  • Rene Herse tires
  • Rene Herse Tire Pressure Calculator