Mountain biking has spent decades improving the bicycle chain.
Hattie Harnden just won a World Cup without one.
The British rider claimed her first elite downhill World Cup victory Saturday at Les Gets, France, producing a 4:11.966 run through rapidly changing conditions to beat Marine Cabirou by 1.232 seconds. Valentina Höll finished third, 1.426 seconds behind, a result that also secured her fifth World Cup overall title with two rounds remaining.
Any first World Cup victory carries weight.
This one came with considerably more.
Harnden's AON Racing machine uses a Pinion gearbox paired with a Gates carbon belt instead of the conventional chain-and-derailleur drivetrain found on most mountain bikes. By putting that system on top of an elite downhill World Cup podium for the first time, Harnden also claimed Gates' €100,000 Belted Purse—a standing bounty for the first elite rider to accomplish exactly what she did at Les Gets.
Suddenly, one of downhill racing's more interesting engineering experiments has a World Cup victory attached to it.
"Downhill racing can be brutal on riders and equipment, so to be the first rider to win on a belt-driven bike is honestly pretty exciting," Harnden said after the victory.
The result wasn't a gimmick, either.
Friday's qualifying had been hammered by rain, leaving the Les Gets course deep, slippery and unpredictable. By Saturday, sunshine had begun drying the track, but riders still faced exposed roots, lingering mud, deep ruts and constantly changing levels of grip.
Harnden found speed where it mattered.
She was particularly strong through the lower steeps and stopped the clock at 4:11.966. Cabirou, racing in front of a home French crowd, couldn't quite match her and finished at 4:13.198. Höll followed at 4:13.392.
The winning margin was 1.232 seconds—roughly half a percent of Harnden's total race time.
That's downhill racing. Small margins, enormous consequences.
And it's part of what makes the equipment underneath Harnden interesting.
Downhill's Gearbox Experiment Gets Its Win
Traditional mountain bike drivetrains place the derailleur and cassette near the rear wheel. Gearbox systems take a different approach, moving the gearing into a centralized unit around the bottom-bracket area.
For downhill engineers, that presents some intriguing possibilities.
Moving drivetrain mass away from the rear wheel can reduce unsprung weight, while the gearbox itself is tucked away from rocks and other trail hazards. A belt can also eliminate some familiar chain-related problems. The trade-offs involve weight, efficiency, complexity, frame design and the simple reality that chains and derailleurs have decades of refinement behind them.
That hasn't stopped several World Cup programs from experimenting.
AON Racing, Atherton Racing, MS Racing and Intense Factory Racing have all pursued belt-driven configurations as manufacturers and teams explored whether the technology could survive—and ultimately outperform conventional equipment—under World Cup conditions.
Gates added a rather large incentive.
The company created its €100,000 Belted Purse for the first elite rider to win a downhill World Cup using its belt-drive system. Riders came close, but the prize survived through the 2024 and 2025 seasons without an eligible winner. Gates brought it back for 2026.
Harnden finally cashed it.
But the signs that a breakthrough was coming had been building.
Harnden had already won an Enduro World Cup aboard a belt-driven Nicolai, although that victory didn't qualify for the downhill-specific purse. AON teammate Reece Wilson then finished second at the Andorra downhill World Cup earlier this season, putting the technology within touching distance of the top step.
Les Gets erased the final step.
AON Was Built to Experiment
The result also says something about AON Racing itself.
Former downhill world champion Reece Wilson established the independent team around an unusually open development philosophy. Rather than simply racing a production bike supplied by a traditional factory sponsor, AON has worked with Swiss manufacturer Gamux to develop purpose-built downhill machinery and experiment with components that might otherwise struggle to find their way onto a conventional factory program.
The bikes look different because they are.
Harnden's setup combines a Gamux platform with a Pinion gearbox and Gates belt drive, while AON has continued experimenting with suspension layouts, frame construction and cockpit geometry across its race program.
That willingness to try something different now has the result every experimental race program eventually needs.
A win.
It doesn't mean the derailleur is disappearing from downhill racing next weekend.
One World Cup victory can't establish that belt-driven gearbox bikes are universally faster, and manufacturer claims about durability or efficiency should be treated separately from what the stopwatch actually proves. Harnden still had to ride the bike faster than everyone else on the mountain.
What Les Gets demonstrated is simpler—and arguably more important.
The concept can win.
At the highest level.
Under ugly conditions.
Against the best downhill racers in the world.
That's a meaningful distinction for technology that, not long ago, sat well outside mountain biking's mainstream.
More Than Just a Technology Story
There is also a danger in allowing the bike to swallow Harnden's achievement.
She earned this.
Harnden moved into downhill after establishing herself as one of the world's best enduro racers, including winning the Enduro World Cup overall before joining AON and shifting more of her attention toward downhill.
At Les Gets, the transition reached another milestone.
Her winning run came against a field containing Höll, Cabirou, Tahnée Seagrave, Gracey Hemstreet and several of the fastest women in the discipline—and on a weekend when the weather made simply staying upright difficult.
Harnden didn't just become the first elite World Cup downhill winner on a belt.
She became a World Cup downhill winner.
There's a difference.
Still, history will connect the two achievements.
Downhill racing has long functioned as mountain biking's laboratory. Suspension systems, geometry, brakes, tires and drivetrain concepts are pushed harder in competition than almost anywhere else, and ideas that initially look strange have a habit of becoming considerably less strange once somebody starts winning on them.
For years, gearbox and belt-drive advocates have argued their technology deserved a legitimate place in that conversation.
At Les Gets, the stopwatch finally gave them their strongest argument yet.
Hattie Harnden crossed the line first.
And there wasn't a chain on her bike.