Atherton Bikes has teased a prototype downhill bike without a derailleur, cassette or chain.
Dumping the traditional drivetrain in favour of what looks to be a Gates belt-driven system with a gearbox – most likely made by Pinion – Atherton Bikes' new A.200.G prototype is a statement of intent.
The drivetrain as we know it has a long track record and plenty of wins under its belt, including for Atherton Bikes’ Charlie Hatton, Rachel Atherton and ex-team rider Andreas Kolb. However, doing away with the derailleur, chain and cassette removes one of the biggest failure points in mountain biking – and boosts suspension performance.
The teaser shot of the A.200.G on Atherton’s Instagram feed shows how svelte the derailleur-less rear end is, potentially helping its rider weave tighter lines through rocks and roots, and reducing the chances of cutting short a World Cup-winning run due to damage.
We’ve all seen the nearly countless heartbreaking moments when a rider’s chain snaps out of the start gate, something a belt drive should all but eliminate.
Although a snapped chain doesn’t always signal the end of a racer’s run – Aaron Gwin famously won the 2015 World Cup in Leogang without a chain – it’s not ideal, especially on flatter, more pedally tracks.
Moving to a belt drive should significantly reduce the chances of this happening.
Aside from snapping, we’ve also seen chains come off the chainring or cassette, once again thwarting a rider’s chances of winning. The belt’s chunky width, singlespeed design and reliable tensioner should reduce this problem.
In a sport where thousandths of a second matter, not being able to shift gears while you’re freewheeling in preparation for the next section seems like an own goal.
Traditional drivetrains need to be rotating for gears to shift properly. That means when you’re on the brakes, freewheeling or deep diving through technical terrain, you can’t change gear.
Most gearbox designs, however, have a constant, driving connection to the rear hub.
The freewheel is inside the gearbox itself rather than the hub, so even when you’ve stopped pedalling, the belt – or chain – continues to rotate.
This means you can shift gears without pedalling to speed up your exit from a corner or technical section.
By getting rid of the cassette and derailleur, you’re reducing the bike’s unsprung mass, which should improve suspension performance.
That means grip, control and – most importantly for a world cup racer – speed, should be vastly improved.
But that’s not all.
As the rear wheel gets lighter, now it only needs a single cassette sprocket or belt cog, the bike’s front triangle gets heavier because you’ve added a gearbox.
This is a real positive because the ratio between the front and rear ends' weights has shifted further.
As the suspension compresses, the lighter rear end now has more to ‘push’ against, so it takes more force to upset and destabilise the bike’s main frame, resulting in calmer handling.
This increase in sprung mass doubles down on the effects of the lighter unsprung mass.
Electric mountain bikes are the best example of this; weighty front triangles are matched with lightweight rears to bring impeccable suspension performance, grip and control.
If you’re not yet convinced, one of the downhill world cup’s largest and most successful teams moving to a gearbox design should persuade you – and put the final nail in the derailleur’s coffin… for downhill at least.
Risk versus reward
However, a wholesale move to gearboxes could be risky.
They’re relatively unproven in competition; although a few teams have run gearbox bikes – such as Zerode and Gamux – none of their riders have quite made it into the podium to prove the design’s mettle.
There are other considerations, too; weight, pedalling drag and resistance, shifting under power, reliability and serviceability all factor in, and help make the vulnerable derailleur look like a safe bet.
The rest of the bike’s construction looks to be relatively unchanged if the teaser YouTube video is anything to go by; it still uses 3D-printed lugs, carbon fibre tubes and the DW6 suspension design I was enamoured with on the shorter-travel A.150.
Moving to a gearbox bike is a risk for any brand, but it’s particularly interesting for the Atherton Bikes race team, given their roster of impressive DH riders.
But with nothing ventured, nothing is gained, which is particularly pertinent if Atherton Bikes is running a Gates belt to link the gearbox and rear wheel.
Dubbed the ‘100k Belted Purse’, belt manufacturer Gates is offering a whopping €100,000 prize fund to the first racer to win a UCI downhill World Cup with a Gates belt-driven bike.
The Atherton team members' track record makes winning it a near-certainty, but other riders have been taking note.
Separately, former world champion Reece Wilson’s new team for 2025 appears to also sport a Gates belt and Pinion gearbox.
On Instagram, the Scot announced his plans with the all-new AON Racing Team and teased his bike, which looks like a Gamux The Sego.
Competition for the 100k Belted Purse is hotting up, and we’re very excited to see how the 2025 racing season unfolds.
