Factor launches ONE: An insane aero bike with 'modern geometry', a barely-legal fork, no stem, and a head tube that could cut fruit

If 2025 will be known for anything in the bike industry, it ought to be the proliferation of mad-looking aero bikes.

Colnago's Y1Rs, Cervelo's S5 and Ridley's Noah Fast 3 are all examples, but none broke the internet as much as when the Factor prototype showed up at the Dauphine.

That same prototype was kindly loaned to us by Factor for our wind tunnel aero bike test, and it stormed to victory, beating the aforementioned trio as well as a dozen others to become the fastest bike we've ever tested.

Now, after months of teasing and leaking, Factor has officially launched it, and it's called the Factor ONE.

The bike, ubiquitously referred to as 'The Factor Prototype' until now, has been a badly kept secret since my colleague Will Jones spotted it in France, with Jake Stewart piloting it to victory days after its leak and half the Israel-Premier Tech team using it at the subsequent Tour de France.

It's also been in the news, with the UCI announcing rules that looked at first as though they'd make it illegal before it even launched. It even made appearances at trade shows such as Eurobike.

Its name was a better-kept secret, though, even though it takes the name of the brand's former aero bike, which itself had an unusual design with a radical double down tube.

The headline figures from Factor, according to its own tests, are that the new ONE is 8% faster than the OSTRO VAM 2.0, 15% faster than the 2024 Cervélo S5, and 22% faster than the Tarmac SL8.

Our aforementioned tests are evidence enough that the new bike is aerodynamically efficient, but despite that and the radically aero-optimised design of the bike, chief engineer Graham Shrive spent very little time discussing the matter at the recent launch event put on by Factor for a handful of media. Just one slide in his 50+ slide presentation, in fact, was spent talking about aerodynamics, while over 40 slides discussed geometry.

I'll touch on many of those details below, but in simple terms, the bike is designed with the modern racing position in mind; further forward, with shorter cranks, narrower bars and bigger tyres.

Crazy design

The standout feature is a crazy wide fork that offers gravel-size tyre clearances – albeit the official clearance for the bike is 34mm – and sits right up against the newly proposed UCI limits, but this is just one example in a sea of wild design ideas.

In another, above the fork sits a bayonet-style steerer tube, which is so narrow it could probably cut through fruit. It enables a seriously deep but impressively slim leading edge, and is paired with a 'chin' fairing that dictates where the airflow goes downstream after hitting the front wheel and the fork crown.

Perhaps most radical of all, though, is the cockpit, which is so different from traditional designs that it technically has no stem, and decouples the steering input from where it's clamped to increase stiffness by 50% while safely offering effective stem lengths up to 150mm.

It's available in eight different fits. There are two different heights; the first is a 'standard' with a 15mm rise, and the second is called 'Hi Rize', with a 35mm rise. The Standard is available in five reaches, simply numbered 1 through 5, each reflecting an effective stem length of 110, 120, 130, 140 and 150mm. The Hi Rize is available in options 1, 2 and 3. Spacers are available to add a small amount of extra stack, but in a way that retains the aerodynamic shape of the front end.

Factor says this answers the call from its pro teams for overly long stems without slowing the steering input, increasing flex, and pushing the rider's centre of gravity too far forward over the bike.

It is currently only offered with a 380mm width, effectively butting up against the UCI's proposed rules on minimum width. Given Factor owns its own factory, it's agile enough to respond to changes quickly, and so is watching the UCI's announcements as closely as the rest of us.

Out back, there's a choice of seatposts too, enabling riders to choose their setback and effective seat tube angle from 73.5° to 77°. In turn, this enables a position as far forward as directly above the bottom bracket, while also enabling riders to match the fit of the existing OSTRO VAM.

Geometry shift

That leads us nicely onto the bike's radical geometry, and as we've already touched on above, the Factor ONE is designed to acknowledge modern road riders' positions and current trends towards bigger tyres, narrow bars and shorter cranks.

One of the key changes, which might be hard to spot at first glance, is the longer top tube and steeper seat tube angle. Together, they lead to a similar effective reach, but in a bike that puts you into a more forward position.

Paired with a longer wheelbase and 5mm lower bottom bracket to offset the trend towards bigger tyres, this creates a racy bike that feels planted, and one where your centre of gravity is lower, and more centralised between the front and rear wheel when compared to adopting a similar position on other bikes, which Factor says has been linked to increased over-the-bar crash incidents in pro racing.

This position then plays nicely with the longer effective stems on the cockpits mentioned above, and is generally paired with shorter cranks, which often means higher saddles and further centre-of-gravity implications – and these can be specced on the One from purchase via Factor's website.

The other effect of the longer top tube is that it enabled Factor to give smaller riders a bigger front-centre, effectively removing the risk of toe overlap without having to change the bike's head tube angle or trail to get there, and in turn, this means uncompromised handling for smaller bikes.

At the rear, to further add to the racy, responsive feel of the bike, the chainstays are a particularly short 405mm.

Factor isn't publishing official weights, but our unpainted, size 56cm prototype model came in at a respective 7.35kg.

Pricing and availability

The One is available at launch in four colours: A black-on-black colourway known as Onyx Black, a 'Nimbus Grey' version with 'ONE' printed in large white lettering all over to create a camo effect, a design called 'Blush' which uses a similar idea but in a seemingly neapolitan ice cream themed pink and yellow, and then my favourite 'Silverstone' which is similar to the Mercedes Petronas F1 team colours of a few years back.

Framesets, which are sold with cockpit and seatpost, will be priced at £6,899.00 / €6,599.00 / $6,900.00.

Full bikes start at £10,899.00 / €10,499.00 / $10,899.00, specced with Ultegra Di2.

SRAM Force AXS builds, complete with power meter, are priced at £11,099.00 / €10,699.00 / $11,099.00.

Stepping up to Dura-Ace Di2 will bring the price to £12,599.00 / €12,099.00 / $12,599.00.

SRAM Red AXS builds, with a power meter, are priced at £12,899.00 / €12,399.00 / $12,899.00.

And finally, in the US and Europe, a Campagnolo Super Record 13 build is available at €12,699.00 / $13,199.00.

All builds are specced with Black Inc 62 wheels.

At this stage, a road test is yet to be completed by the Cyclingnews team, but I will be sure to bring you a full review as soon as possible.