The Flint Hills are totally different from the Cascade Mountains where I usually ride, but equally fascinating. Flying here yesterday, Kansas seemed flat, but the Flint Hills are anything but. The climbs are shorter, but relentless. The rocks are chunky and can be sharp. The climate is hotter, especially at night. It’s really a different world. When I came here two years ago, I loved it so much that I vowed to come back. So here I am, ready to head out on a recon ride on my bike.

As two years ago, I’ve entered Unbound XL: 350 miles, 17,000 ft of climbing. (That translates to 565 km long and 5,200 m up.) We all come here for the adventure, and we leave with life-long memories.

This year, the courses head to the north of Emporia, where the gravel is rougher and the hills are steeper than in the south. That’s why I brought the Unbound XL bike we built two years ago for Mark. Last time, I rode the Oregon Outback bike with Nivex derailleurs. I love that bike, but it’s more road-oriented, if you will. The Unbound XL bike is the one I choose when the terrain straddles the line between gravel and mountain biking. That’s when the one-by, huge spread of gears, and electronic shifting come in handy.

In addition to Unbound XL, the bike has tackled the Arkansas High Country Race (twice) and the Dark Divide 300, plus numerous other adventures in the Cascade Mountains. This bike takes a different approach from most gravel race bikes. There’s a reason for that: Unbound XL is a different event from most gravel races.

Riding for 25+ hours and 350 miles is much longer than most gravel races. I need lights and clothes for the night. And since it’s unsupported, I need to carry supplies. In the 200-mile event, riders have two resupply stations where support teams meet them with clothes, food and other equipment. In the XL, we don’t have that luxury. (That also means logistics are much easier!)

Why not a bikepacking setup? Unbound XL is much shorter than bikepacking races. There’s no sleep, hence no need for a sleeping bag, bivy or tent. These single-push races over 350-500 miles are closer to randonneuring than to any common type of racing. It’s a unique sport that hasn’t caught the attention of the bike industry. And yet Rene Herse Cycles has 85 years of experience with bikes and components for exactly this type of event. In 1938, René Herse started our company by entering an ultralight bike in the prestigious Concours de Machines. The goal was to create the lightest, fastest and most reliable bike for riding 750 km (470 miles) over rough gravel roads in the mountains. Sound familiar?

It’s easy to see a steel bike and think ‘retro,’ but the real reason I chose steel is customization. With steel, anything is possible. Carbon bikes require expensive molds. Making one-offs is not feasible—you have to commit to a production run of hundreds or thousands of frames. (With a one-off, we didn’t want to make decals, so we chose to show our inspiration with the hand-lettered logo.)

Customization in this case means that every component—even the bag—has been part of the design from the beginning. With steel, we can use slender fork blades that can flex on rough surfaces. The difference is noticeable, and the feel is similar to gravel suspension forks like the Lauf Grit that provide 30 mm of suspension. With steel, we can also fabricate a fork crown to clear ultra-wide tires. Lights and bags aren’t add-ons, but part of the original design.

That eliminates brackets and adjustable sliders. That saves weight: The complete bike weighs just 10.3 kg (22.7 lb). “Not very light,” I hear you say, but consider that this weight include the lights, the rack, as well as pedals, bottle cages and even the pump. Add all those pieces to a carbon race bike, and it’ll probably weigh as much or more. Having all these parts seamlessly integrated also improves reliability. In fact, this bike hasn’t even been overhauled (and barely cleaned) since it did the 500-mile Arkansas High Country Race a few months ago. I checked all the bolts, but none needed tightening.

I’m running a 1×12 with a 36-tooth chainring on the front and a 10-44 XPLR cassette on the rear. Shifting is via a SRAM XPLR electronic derailleur. I really appreciate the quick and reliable shifts. The ultra-low gears may come in handy on the punchy, rocky climbs late in the race, when my legs are starting to get tired.

Tires—everybody is talking about tires at Unbound. At 54 mm, my tires are wider than most. Tires that wide allow me to run extremely low pressures—probably about 21 psi (1.5 bar). This in turn allows me to run a lighter, more supple casing for extra speed and ride feel. Inside the tires are the new Rene Herse TPU tubes.

Why not tubeless? Speed and durability. TPU tubes are considerably faster than liquid sealant sloshing around inside your tubes. And with the tube reinforcing the tire sidewall, cuts are much less likely. The downside is that if I cut a tire, there’s no sealant to (hopefully) seal the cut. I’ll have to change the tube. Fortunately, with TPU tubes being so light and small, I can take plenty of spares. Let’s hope I don’t need them!

The cantilever brakes are also an unusual choice on a modern gravel bike. There’s nothing wrong with discs, but the cantis are lighter and simpler. They have as much braking power on loose surfaces, where traction limits how hard you can brake. (They also make it possible to use flexible fork blades, as the braking power isn’t transmitted through the hub into the fork, as it is with disc brakes.)

In Unbound XL, we’ll ride for more than 9 hours in the dark, so good lights are essential. For me, it’s hard to imagine riding rough descents at night without being able to see far ahead. A layered beam—as found on car headlights—puts more light into the distance, where you need it, and less right in front of the bike, where it creates a bright spot that makes it hard for your eyes to adjust to the darkness. Once experienced, the difference to lights with simple round optics is huge.

Mounting the light low also accentuates irregularities: Rocks and bumps cast shadows. A helmet light is worst in that respect, as the beam is aligned exactly with your line of sight. Think of the low light as a permanent ‘Golden Hour’ just before sunset, when everything seems more crisp and shapes are more pronounced. Perfect for seeing those big rocks far in advance, so you can avoid them.

Powering the light is an ultra-reliable generator hub. It’s lighter than batteries that last 9 hours, and I don’t ever have to worry about run times. You see SON generator hubs on more and more gravel bikes for those reasons.

Having lights available anytime, at a turn of a switch is really nice. In my case, the light switch is on top of the stem. On a bike full of custom solutions, it’s a nice touch, but not essential by any means.

Handlebar shapes are not something tech guides talk about a lot. For shorter rides at very high power, a racer’s hands barely touch the bars. Almost any bar shape will do.

In longer events, numb hands and even nerve damage are common. The Rene Herse Randonneur bars may look unconventional, but they’ve evolved from a shape that has been fine-tuned for decades. The upsweep provides three-dimensional support for the palms of your hands to eliminate pressure points. (The palms of your hands aren’t flat when you hold the bars.) This works so well that I’ve stopped using gloves for these long adventures. I found that gloves can bunch up and cause blisters—and I just don’t need them any longer.

The leather bar tape is another ‘Why not?’ thing: If I’m touching the bars that long, they should feel nice. The bike’s handling is stable and intuitive, so I don’t need grippy tape that velcros my hands in place. The bike’s sure-footed handling also allows me to run narrow handlebars (40 cm in the drops, narrower on the tops) for better aerodynamics. I don’t need leverage to wrestle with the bike—like a good road bike, it responds to a light touch and goes where I guide it. (However, I understand and respect riders who prefer vegan options for bar tape and saddle.)

The waxed canvas bag is part of the lightweight approach. It’s hard to believe, but since it doesn’t need stiffeners or waterproof liners—the material itself is waterproof—this bag is much lighter than bags made from synthetic materials. It’s empty in the photo, so it doesn’t hold its shape well. That won’t be a problem once I add clothes and food for the 27+-hour ride.

When we tested the bag in the wind tunnel, we found that it’s more aero than no bag at all, especially when I tuck narrow and low on fast downhills. Speaking of aerodynamics, that’s also the reason for the short fenders. They are fairings that shield the tire tops—which are rotating at twice the speed of the bike—from the oncoming air. Moto GP bikes use the same type of fenders, because they make a big difference. In the wind tunnel, we found they offer a similar benefit to aero wheels. Why no aero wheels? They don’t work well with ultra-wide tires, because you’d need very wide rims, and they would have to be so deep that they’d become difficult to ride in crosswinds.

Overall, it’s a pretty unorthodox approach to a gravel bike. It comes out of decades of experience with bikes for long single-push rides over all kinds of terrain. I was riding one of the shorter distances—without night riding and with support—I would probably ride my OPEN U.P.P.E.R. carbon bike. What I wouldn’t have changed are the essentials: a one-by drivetrain with electronic shifting. Comfortable, truly ergonomic handlebars. And tires that are as wide and as supple as possible.

Wish me and all the other riders in Unbound luck! It’ll be fun and an incredible experience. As we continue our preparation for the big ride, we’ll look at tire pressure tomorrow.

More information:

  • Aerodynamics of gravel bikes
  • Beam shapes and why they make such a big difference
  • Rene Herse handlebars