Power analysis: Ian Boswell’s ride at Unbound Gravel

In the wee hours of the morning in a little town called Emporia, Kansas, hundreds of cyclists from around the world roll up to the start line of Unbound Gravel, the biggest gravel race in the world. Gravel racing has exploded in popularity in recent years, and only in the last few has the clientele reached the World Tour. It’s almost a different sport – gravel racing versus road racing – in that it is so, so lonely. There are no support vehicles, no lap counters, and no cheering fans apart from the occasionally confused farmer. There are aid stations, but those only come every 50 or so miles. If you break your bike or run out of food, you’re on your own.

Of course, there’s the physical difficulty too. Few cyclists have ever ridden 200 miles on the road, let alone raced it on gravel. And the Flint Hills gravel of southern Kansas is no joke either – I’ve ridden it myself. This is not the kind of gravel that you enjoy. After my first hour-long ride on this mixture of dirt and shattered stones that you call ‘gravel’, I think my hands hurt more than my legs.

Completing the Unbound Gravel 200 is an achievement of its own, but to win it is to become the unofficial King or Queen of Gravel. And in 2021, Ian Boswell and Lauren De Crescenzo earned their titles. This is what it took for Boswell to win the Unbound Gravel 200.

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It all started innocently enough in downtown Emporia. At 6:00 am local time, the Unbound Gravel 200 field rolled out for 206 miles of pain. The weather forecast predicted 20-30mph winds and 32-37°C (90-100°F) temperatures for the majority of the day – I’m not sure there was a single rider who was happy about that.

Positioning is crucial in gravel racing, especially a race as big as Unbound Gravel. With hundreds of riders on the start line, there was a huge fight for the lead heading into the first gravel sector. Just three minutes into what will be a 10+ hour day, Boswell was already making a big effort at over 400w to hit the gravel in good position.

Boswell – early fight for position:
Kilometer: 1
Time: 1:04
Average Power: 433w (6.3w/kg)

The first hour of the race was the easiest of the entire day for Boswell (see below for Boswell’s hour-by-hour power splits), with an average under 200w. This was probably in large part due to the fact that there was little wind at 6:30 in the morning, and even so, it would have been at the riders’ backs. It wasn’t until kilometer 66 that the pace really heats up, and when it does, it happened quickly.

Boswell – pace heating up:
Kilometers: 66 to 97
Time: 53:38
Average Power: 298w (4.3w/kg)
Normalized Power: 336w (4.9w/kg)
Peak 1-min Power of the race: 515w (7.5w/kg)
Peak 10-min Power of the race: 334w (4.8w/kg)

Heading north on Divide Road, Boswell set his peak 10min power of the race, as well as his peak 1-min power within the same effort. On some of the steepest climbs of the race, he hit over 600w while barely maintain 15kph, and then went blasting down the other side at 50+kph. In his peak 1-minute-effort of the entire race, Boswell attacked a 13 percent grade at 515w (7.5w/kg) for a full minute. That’s a huge effort for anyone, and this one came with over eight hours to go.

From kilometers 118 to 160, the race headed into more steep climbs, and even more crosswinds. On Little Egypt Road, the front group split down to seven, including Boswell, Ted King, Peter Stetina, Laurens ten Dam, and defending Unbound Gravel champion Colin Strickland. At more than five hours into the race – but not even to the halfway point – Boswell did his peak five-minute power of the race, holding a normalized power of nearly 400w (5.8w/kg) for five minutes.

Boswell – making the lead group:
Kilometers: 118 to 160
Time: 1:20:04
Average Power: 280w (4.1w/kg)
Normalized Power: 307w (4.5w/kg)
Peak 5-min Power of the race: 364w (5.3w/kg)
Peak 5-min Normalized Power: 394w (5.7w/kg)

At this point in the race, the lead group finally settled down, seemingly content with its own composition. For the next couple of hours, the leaders rotated steadily, only losing two riders due to mechanicals or fatigue.

Over 250 kilometers into the race, the lead group then turned into a nasty headwind for the final few hours of racing. The temperature has now climbed to over 32°C (90°F), and it will stay there for the rest of the day. Around Lake Kahola at Kilometer 290, Stetina attacked and got a gap on the rest of the group. Boswell dug in and worked with the chase, and all of a sudden, there were only two riders left: Boswell and ten Dam. King was dropped, Strickland suffered a mechanical, and Stetina dropped his chain – all some of the joys of gravel racing.

Boswell – Stetina’s attack:
Kilometers: 286 to 300
Time: 26:43
Average Power: 292w (4.3w/kg)
Normalized Power: 315w (4.6w/kg)

Boswell and ten Dam couldn’t shake each other – it was going to come down to a sprint. Boswell led it out, neither are strong sprinters, but at the end of a 10-hour race, anything can happen. As soon as ten Dam jumped, so did Boswell, and the two dirt-covered men pushed and churned and gritted their teeth for the last 200 meters; and Boswell came out on top. For a guy who doesn’t back his sprint, he was still able to hold 912w for the final 15 seconds, at the end of a 10-hour day. Impressive, to say the least.

Boswell – final sprint:
Kilometer: 331
Time: 0:18
Average Power: 856w (12.4w/kg)
Max Power: 1,032w (15w/kg)

If you’re looking for the magic sauce, this is it – this is how you win Unbound Gravel.

Hour 1
Average Power: 192w (2.8w/kg)
Normalized Power: 224w

Hour 2
Average Power: 219w (3.2w/kg)
Normalized Power: 279w

Hour 3
Average Power: 287w (4.2w/kg)
Normalized Power: 326w

Hour 4
Average Power: 265w (3.8w/kg)
Normalized Power: 292w

Hour 5
Average Power: 274w (4w/kg)
Normalized Power: 303w

Hour 6
Average Power: 253w (3.7w/kg)
Normalized Power: 273w

Hour 7
Average Power: 233w (3.4w/kg)
Normalized Power: 249w

Hour 8
Average Power: 228w (3.3w/kg)
Normalized Power: 259w

Hour 9
Average Power: 239w (3.5w/kg)
Normalized Power: 259w

Hour 10
Average Power: 271w (4w/kg)
Normalized Power: 294w

200 miles is a long day, especially on the Flint Hills gravel. Add in 20-30mph headwinds and scorching heat, and this could be the hardest ride of your life. I could dig into the details for hours – looking at every climb and descent, what peak power Boswell is hitting, what cadence he is using on the climbs versus the flats.

But what it really comes down to is his resistance to fatigue. Pro bike riders are among the fittest humans in the world, and they’re able to hold a pace that few of us could manage for an hour. Throughout the Unbound Gravel 200, Boswell’s average power (and normalized power) stays right around 4w/kg. The only easy outlier was the first hour, but to be fair, that was at six in the morning.

Hours 3, 4, and 5 were definitely the hardest, with the race splitting down from hundreds to less than 30, and then from 30 to 12. Hours 6-9 were mostly a battle of attrition, thanks to a cooperative front group that really didn’t want to get caught. In the final hours, the pace heated up again, and this is where the race was won.

After burning more than 7,000kJs, and riding near 4w/kg for more than 8 hours, Boswell is still able to accelerate at 400w up climbs, and close down attacks at over 500w. He doesn’t bonk, he doesn’t tire, and he doesn’t cramp. Not having a mechanical was a big part of it too, but that’s a story for another day.

In the end, it’s Boswell’s world-class endurance and resistance to fatigue that put him a step above the rest. And, he was still able to hit more than 1,000w in the final sprint. Ian Boswell is the new King of Gravel.

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Boswell – Unbound Gravel:
Kilometers: 331
Time: 10:15:01
Average Power: 247w (3.6w/kg)
Normalized Power: 280w (4.1w/kg)
Max Power: 1,032w (15w/kg)
Energy Burned: 9,106kJs
Elevation Gain: 3,293m (10,803ft)

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Power Analysis data courtesy of Strava
Strava sauce extension 

Riders: Ian Boswell