core4 – Iowa’s All-Surface Battleground Joins the Gravel Earth Series

By James Ion, Editor - Photography provided by core4

This weekend sees the return of core4 to Iowa, this time as part of the Gravel Earth Series. With big prize money and GES points on the line, it has attracted a stellar field. We had a look at the race, its history, its format and who will be fighting for the win.

History

The Midwest doesn’t do half-measures. When Iowa City decided to put itself on the gravel map, it didn’t simply add another road to nowhere race — it created core4. Born in 2022, inspired by Bentonville’s Rule of Three, it stitched together every surface in reach: champagne gravel, dirt-rich B-roads, winding singletrack, and just enough pavement to make you question your gearing.

The idea was simple, the ambition anything but: make an event that felt both like a world-class race and a neighbourhood party. In just two years, it went from being a local curiosity to drawing nearly a thousand riders, and in 2025, it takes the next step — joining the Gravel Earth Series as the lone Heartland stop on an otherwise global tour. For a race that began with a handshake and a scribbled course map, that’s no small leap.

Ethos

Core4 is more than four surfaces. Its four pillars: Community, Opportunity, Recreation, and Engagement. A creed as much as an acronym. It’s the organisers’ way of saying, This is for everyone.

The event celebrates all the cats, all the peeps — pros and beginners, locals and out-of-towners, geared racers and single-speed eccentrics. Juniors ride free, e-bikes get a nod, and the last finisher gets almost as loud a cheer as the first. Some leave with trophies; others leave with free tattoos.

There’s a current of generosity running through the event: partnerships with local advocacy groups, a finish festival that feels like a homecoming.

Alex Buhmeyer, “Is this my event? Hell no. It’s everybody’s.”

Format

Two days, four distances, one orchard.

Friday night: an optional trail run weaving through Wilson’s Orchard, a playful prologue under Iowa’s summer light.

Saturday: the main event. Distances from 20 to 100 miles. The short courses are sociable “crew rides” — no timing chips, no singletrack, just good gravel and good company. The long courses — 60 and 100 miles — are where it gets serious: four surfaces, sharp handling, and the coveted spots on the podium.

The 100-mile “Stone Crusher” is the Gravel Earth Series points race. Separate pro waves for men and women, a $10,000 prize purse split evenly, and categories broad enough to make room for everyone from U18 juniors to 70+ veterans.

No time cuts. No broom wagon shame. And if you do happen to roll in last, you’ll be met not with pity, but with a champagne shower.

Course

core4 wears its tagline like a promise: no surface untouched.

From the orchard start, the route drops riders onto Iowa’s best gravel — smooth and fast under a big sky. Soon, it dives into the Level B roads: farm-track dirt that bakes hard or bogs deep depending on the week’s weather. If it’s wet, the organisers have “plan B” detours. If it’s dry, expect dust, ruts, and a grin you can’t wipe off.

Then comes the singletrack. Local MTB gems like Sugar Bottom and Woodpecker twist the rhythm, forcing gravel bikes into tighter, more technical lines. For some, it’s joy. For others, it’s survival.

Somewhere in the middle, you’ll find yourself rolling through Iowa City’s urban ribbon — a brief, surreal reminder that civilisation exists before the route spits you back into farmland.

And then, the finale: a short, brutal grass climb into the orchard. A cyclocross-style curtain call where the crowd closes in and cowbells echo off apple trees.

Organiser Perspectives

Alex Buhmeyer and his crew know what they’re doing — and what they’re not. They’re not chasing size for its own sake. They’re not trying to be the next corporate mega-race. They are, however, chasing the perfect balance between race and party.

“Delivering quality over quantity is the target,” says Buhmeyer. “We want to keep promoting active and healthy lifestyles within our community and having fun while doing it.”

Co-founder Nate Kullbom — also a two-time champion — designed the first course entirely from memory, a love letter to his local roads and trails. Liz Martin, of Bike Iowa City, weaves in the community connections. Together, they’ve built an event that now has European gravel series organisers calling them.

Rider Perspectives

core4 has a knack for converting suffering into nostalgia. Riders finish covered in dust or mud, recounting the day’s technical chaos over a pint, already plotting their return.

Pros have taken notice. Gabriella Arnold, last year’s women’s champion, praised the equal prize money and the effort to get more women racing.

Drew Dillman, the men’s champ, called it one of the most fun — and hardest — days on a bike he’s had in years.

Amateurs echo the sentiment. For some, the singletrack was a revelation; for others, the B-roads were the crucible. Everyone, it seems, talks about the orchard finish.

Notable Winners

• 2022 & 2023: Nate Kullbom and Vanessa Curtis, local royalty.

• 2024: Drew Dillman and Gabriella Arnold — a shift toward national and international talent.

The DFL award? That went to a grinning John Wrobel in 2024, doused in champagne for his stubborn finish.

Reviews

Betsy Welch (Velo) called it “a huge success”. The Gazette praised its growth without losing charm. Social media calls it “the best finish line party in gravel”.

The consensus: it’s serious racing wrapped in a good-time package. You’ll hurt. You’ll laugh. You’ll come back.

Pro Start List – 2025

• Drew Dillman (USA) – Defending men’s champion, technical ace.

• Chase Wark (USA) – 2024 runner-up, sprint threat.

• Innokenty Zavyalov (USA) – Lifetime GP racer, diesel engine.

• Nate Kullbom (USA) – Two-time champ, course architect.

• Gabriella Arnold (BER) – Defending women’s champion.

• Karolina Migoń (POL) – Confirmed. GES overall women’s champ, 2025 Traka 360 winner.

• Tobias Kongstad (DEN) – Confirmed. Traka 360 men’s champion, European gravel powerhouse.

• Geerike Schreurs (NED) – Confirmed. Mrs Consistent, on the hunt for GES points.

• Morgan Aguirre (USA) – Confirmed. Rising U.S. star, 2024 GES podium finisher.

Likely contenders: Sarah Sturm, Vanessa Curtis, Griffin Easter.

This year’s field blends local legends, defending champs, and European heavyweights. It’s the most international, most competitive core4 yet — and whoever wins will have earned it on Iowa’s all-surface battleground.