Strap yourselves in for our Unbound tech bonanza

By Ben Delaney

Published: Monday, 05 June 2023 at 12:00 am

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Unbound is the world’s most important gravel race, with the 200-mile distance serving as the marquee event for the Life Time Grand Prix series that has $250,000 on tap. There is also the 350-mile XL, plus 100-, 50- and 25-mile events.

Held on the rolling Flint Hills outside Emporia, Kansas, the race is notorious for tough conditions.

Sometimes it’s blisteringly hot and humid; some years it pours rain. Perhaps the most difficult is when rain hits dirt roads that don’t drain well, and soupy mud turns to ultra-sticky, peanut-butter mud that brings wheels and riders to a standstill, and ejects chains from chainrings.

While the forecast for this weekend’s race was largely dry, rain the day before sent many riders scrambling for thinner tyres for better mud clearance. And boy did they need it. Conditions for Unbound 2023 made for a particularly challenging edition of the event – for riders and their bikes alike.

Tyre selection varied wildly; some riders had 38mm slicks, and others had 2.1in knobbly tyres. Outside of the 70 Grand Prix competitors, gear selection is an even wider cornucopia, with everything from singlespeeds to fat bikes and tandems seen in the Flint Hills.

We’ve already covered the new Shimano GRX groupset and the new Canyon Grail spotted at Unbound, so let’s get into the tech detail.

Here’s our Unbound 2023 gravel tech mega-gallery, covering everything from tyre choices and puncture precautions, to aero setups and custom hacks, as well as the bikes of some of the fastest riders in the race.

Tyre choices

No other piece of gear is more discussed or fretted over at Unbound than tyres. While the top riders are limited to their sponsor’s options, there are still myriad choices for tread, width, pressure and the use or tyre inserts or not. 

With rain soaking parts of the course and rendering some miles-long stretches difficult if not downright unrideable, many riders opted for skinnier than usual tyres, in an attempt to cut through the mud and leave additional clearance between the frame and tyre. A few riders ran a knobbly tyre up front and a slick in the rear.

Lachlan Morton chose a mismatched tyre setup. He paired a 44mm rear tyre with a massive 2.1in front tyre. 

Morton ran the Vittoria Terreno Dry up front, with a slightly more knobbly tyre on the rear.

Note also his wheel choices. A 60mm-deep Vision Metron front wheel was likely there to eke out every aero saving possible. A lower rear wheel might have been chosen for weight-saving purposes.

Ben Delaney / Our Media

While there were muddy parts of the course, the overall theme was still for a fast race, so riders tended to stick to slick, or semi-slick treads. 

Innokenty Zavyalov, for example, ran full slicks, simply sizing down for the mud.

Ben Delaney / Our Media

With a number of Specialized-sponsored riders taking part, there were a good number of the company’s Pathfinder tyres on display. They’re a popular option for non-Specialized riders, too.

Ben Delaney / Our Media

Intermediate treads were also popular, with riders aiming to combine traction in the mud with fast-rolling speed anywhere else.

The Maxxis Rambler was a common sight, while the Schwalbe G-One RS is another Unbound favourite having been launched at the race last year.

Ben Delaney / Our Media

AG2R’s Larry Warbasse, meanwhile, was rocking a set of Pirelli Cinturato RC X tyres.

Pirelli launched the Cinturato Gravel RC last year as a mountain bike-inspired gravel tyre, with a heavily lugged tread pattern for grip.

We’re not familiar with the ‘X’ version used by Warbasse, though. Is this a new tyre?

Ben Delaney / Our Media

Puncture precautions

Unbound takes place over the Flint Hills of Kansas and, well, the clue is in the name.

Ride a bike through these hills of flint and you’re almost guaranteed an enforced rest to fix a puncture.

With no follow car to bail riders out, having tubeless tyre plugs (aka bacon strips) at the ready is key for anyone who wants to stay at the sharp end – and anyone who just wants to survive the race.

Ben Delaney / Our Media

Fixing a tubeless puncture quickly is crucial in a race, so several riders opted to tape Genuine Innovations’ bacon strips to the front of their bike, ready to plug a flat. Others had little Dynaplug canisters at the ready on their bike.

Lachlan Morton had two bacon strips already in their plugging tools, taped to his Di2 cables on the handlebar, ready for the fastest deployment. An F1 engineer would be happy with that.

Ben Delaney / Our Media

Tobin Ortenblad, meanwhile, had his tubeless plug tool strapped to the seatpost, which might seem like the muddiest place possible to mount a tool.

Ben Delaney / Our Media

That is, until you see Russell Finsterwald’s effort. His bacon strips, wrapped around the brake hoses, were completely caked in mud by the finish. At least it looks as though he didn’t need them.

Ben Delaney / Our Media

Storage solutions

Unbound is one of the toughest single-day races on the calendar, subjecting both bike and body to an almighty test. Preparation is key – and that means having everything you need for, in the case of Unbound XL riders, 24 hours or longer in the saddle.

Some of the racers in the shorter distances will get away with storing their essentials in their jersey pockets – but once you get up to the 200- and 350-mile distances, you’re likely to need a bag or two.

However, not everyone got the memo. Laurens ten Dam and Larry Warbasse were two riders in the elite 200-mile race who went without bags, beyond a small saddle pack.

The Specialized Diverge of ten Dam does, however, feature frame storage under the front bottle cage.

Ben Delaney / Our Media

Lachlan Morton chose a slightly odd place to mount his one storage bag, tucking it in front of the seatpost. The triangular Tailfin bag isn’t a design that is available yet, and comes from the company’s R&D department.

Ben Delaney / Our Media

The 350-mile XL race sees the number and size of frame bags increase.

Ben Delaney / Our Media

XL racers also compete unassisted, meaning they must carry all their food and water or stop at stores on the course.

Ben Delaney / Our Media

And if you’re going through the night, as is the case with the XL 350-mile racers, you’re going to need lights. This fork-crown mounted front light is a very neat solution from Luke Hall.

Hall also has a charging cable running from his Wahoo computer to a battery pack, which is probably a good thing to have if your ride is going to take over 24 hours.

Ulrich Bartholmoes

Ulrich Bartholmoes, meanwhile, used a Supernova Airstream 2 front light, mounted very neatly in line with the head tube.

Ulrich Bartholmoes

His BMC Kaius featured a very tasty build with a Rotor InSpider power meter, SRAM GX Eagle AXS derailleur complete with a Kogel oversized pulley wheel cage, and Lightweight Pfadfinder Evo Disc wheels wrapped in 40mm Hutchinson Touareg tyres. 

Ulrich Bartholmoes

An Apidura frame bag keeps storage inside the frame’s front triangle.

Aero bars for the masses

Banned this year for the elite 200-mile competitions, but allowed in all the other fields, aero bars continue to be important in endurance gravel.

For the fast riders, it’s about aerodynamics. For many amateur riders, and even many elite riders in the XL, it’s a comfort thing, because they allow a change of hand position and take weight off the hands and wrists.

Ben Delaney / Our Media

Even in the elite 200-mile fields, some riders found a workaround. Innokenty Zavyalov fitted a section of bar tape to the flat section of his handlebar. This enabled him to rest his forearms on the bar, mimicking TT arm rests.

Add in a long Garmin Edge 1040 computer to hold onto and you’ve got a makeshift aero bar setup.

Away from the 200-mile race fields, women’s XL winner Legan fitted a set of aero bars for the ultra race.

Her efforts paid off, winning the event by a healthy margin.

Aero elsewhere

If you’re doing big distances at race pace, you want to be efficient. That means aero is going to play a big part in your bike and clothing choices, even before TT bars become a consideration.

Factor’s Ostro Gravel is the perfect example of this. Lauren De Crescenzo’s bike featured a special paintjob for the race, with the frame boasting numerous aero touches.

The head tube has an hourglass shape, with the central section narrowing to smooth the airflow through the rest of the head tube. 

Deep tube shapes come straight from the Ostro VAM, Factor’s fastest road race bike, while a Black Inc bar helps the brake hoses stay hidden.

De Crecenzo’s bike features a CermicSpeed oversized pulley wheel system, mounted to a SRAM Red rear derailleur. The 1x 48-tooth aero chainring is mounted to a SRAM Red power meter crankset.

Finishing the bike is a set of Black Inc 34 wheels and lovely Rene Herse tyres.

Ben Delaney / Our Media

De Crescenzo was far from alone in riding an aero-optimised gravel bike.

Life Time Grand Prix racer Hannah Shell took to an aero-profiled Cervélo Aspero-5, while, as we’ll come on to, Larry Warbasse hopped on the racy BMC Kaius.

As the gravel bikes category evolves, we’re seeing a distinction between race-focused (read: aero) bikes with generous tyre clearance and aggressive (for gravel) geometry, and machines aimed at even bigger, burlier adventures.

In the case of BMC, the brand has the Kaius as its ‘performance’ gravel bike and the micro-suspension equipped BMC URS as its ‘exploration’ gravel bike.