Perhaps not since the 1990s, when space-age carbon monocoques and bikes made from washing machine parts stole all the headlines, has the cycling world reacted so feverishly to a new design. On June 12, 2025, Jake Stewart won stage five of the Critérium du Dauphiné on a mystery Factor prototype that was instantly branded “wild”, “mind-blowing” and “insane”. If the Colnago Y1Rs of Tadej Pogačar and his UAE Team Emirates had upset the applecart then this bike was hurling it a mile into the air. If the peloton was already full of aero smoothies, Factor had brought the blender.
At a glance it was easy to identify influences from Factor’s Hanzō Track. That bike had been designed especially for the Australian team to use at the Paris Olympics in 2024, where they won gold in the team pursuit and broke the world record. Notably, the new road bike had the Hanzō’s wide fork stance and head tube design. But there were other elements that were strikingly different from anything else out there and that we could only speculate about.
Now Factor has pulled back the curtain and revealed all the details about the new bike, which is called ‘One’ – a name it has revived from its past. I test rode it in Girona, Spain at a pre-launch for selected media in September, and it is every bit as wild, radical and mind-blowing as the headlines suggested it would be when it was first spotted. But what’s perhaps hardest to get one’s head around is that once it’s all explained – and more importantly once it’s ridden – everything that looked outwardly insane makes total sense in the context of modern road racing. It’s not often that something can be the fastest and the most sensible at the same time, but the One absolutely is.
There’s a lot to unpack. The top line is that the One is the world’s fastest UCI-legal road bike. According to Factor’s data it’s over 8% faster than its own Ostro VAM, around 15% faster than the Cervélo S5 (2024 version) and 22% faster than the Specialized S-Works Tarmac SL8. And at higher yaw angles beyond 15 degrees it outperforms them yet further.
But there’s much more to it than just drag performance in the wind tunnel. That’s only half the story, or perhaps even less. Here’s Factor’s official line:
“When the UCI relaxed key design regulations, we were ready. We pushed to the very edge of what is now possible, not only aerodynamically, but in rider fit and handling. Advances in computational fluid dynamics (CFD) gave us unprecedented insight into airflow, letting us iterate hundreds of virtual prototypes before ever stepping into a wind tunnel. Every decision was tested, refined, and proven, on screen and on the road. But this isn’t just about cutting through the air. We studied the changing position of the modern racer: rotated forward over the front of the bike, saddles pushed further forward, shorter cranks, narrower bars, longer reach. The UCI has responded to these trends with new rules, and the One is designed to embrace them, putting the rider in their most powerful position while maintaining perfect handling balance and centre of gravity.” Let’s look at the aerodynamics first.
Aerodynamics: to the edge of legality
According to Factor, when the UCI began relaxing long-standing dimensional constraints, especially around the conceptual fork ‘box’, into which it must fit, most brands saw an incremental design opportunity. But, says the brand, “We saw an open corridor to the edge of legality.”
Bicycles' aero improvements had been focusing increasingly on the leading edge as opportunities for saving watts became harder to find. We’ve mostly seen slimmer, deeper head tubes, but Factor’s interpretation of the UCI’s rule changes led it to cover sections of the fork with the down tube box, which was previously not allowed. In the case of the Hanzō Track, the fork in its entirety was neither contained within the fork box nor the head tube box. Director of engineering, Graham Shrive, says: “With the One, we were able to cover over that tail portion of the fork with the down tube box. That’s a subtle, small change that for us had a really big impact in the way that we designed the fork, the bike, and what we’re doing with the aerodynamics. That’s what unlocked the whole forward-set fork.”
The One’s fork is a bayonet design, functioning more like a hinge than the traditional steerer tube type. This is not a new idea and was deployed effectively by brands such as Look during the 1990s. The original Factor 001 of 2009 used a dual bayonet design, and the latest Colnago Y1Rs, as used by Tadej Pogačar and UAE Team Emirates, uses it too. Like the Colnago, the Factor also features a gull-wing bar that smooths airflow from the bar top section onto the top tube. However, with the new One, Factor has manipulated the front-end structure so that it includes a prominent “chin” – an extended fairing that thrusts forward of the head tube that is engineered to manage the spillover of drag when airflow detaches from the front tyre and crown area of a traditional design.
Shrive and his team validated the design by comparing wide fork leg spacing against narrow, and a ducted v non-ducted chin, upswept v downswept bar as well as brake and bottle cage position variations. He explained that advancements in CFD modelling, along with Factor’s ability to rapid prototype, since it owns its own factory, enabled this. And not only the shapes from the Hanzō but also the learnings from developing it played a key role. “One thing with the Olympic programmes is they will push you way past your comfort point. They wanted to win gold. And [Factor founder] Rob Gitelis was very clear that we were prepared to help them win gold and we pulled out all the stops. We effectively shut down the company for about a year and were 100% focused on that bike. And what we started to find was a lot of our assumptions [about aerodynamics] started to fall away.”
Geometry: enabling the modern racer’s position
Factor lists its primary objective in terms of geometry as: “To enable the modern racer’s position without destabilising handling or rider confidence. According to Shrive: “Part of the project was to query fitters, mechanics, the riders themselves… where do you see your fit going next year? What is limiting you on your current bike and what can we do differently?"
He continues: "We’ve got four or five guys left on the team with setback seatposts. Just five years ago, that was probably the other way round. Predominantly, these are the older riders. When Chris Froome came onto the team he pushed us really hard to do a negative 5° seatpost. Zero [inline] wasn’t enough. We actually went further forward. So it’s been clear we had to do something with the seat tube angle for the way riders are sitting on the bike now. He continues: “We had riders in potentially unsafe positions. There’s always a request every year for 150mm stems. It’s just too long to put on a conventional steerer tube.
“If you’re going from a 175mm crank to a 160 or a 150 crank, that should change how you sit on the bike,” he continues. “As a manufacturer, if you just start shipping a bike with a 160 crank without changing anything else you’re doing a disservice to the rider. Similarly, as the tyre size increases, the trail increases. If I write into our geometry guide that the trail is 59mm because it’s based on a bigger-diameter tyre, people are going to think it’s a slow-handling bike. So how do you reconcile those things? You can’t live in denial and still use the outside diameter of a 23mm when nobody is riding it.”
So Shrive and his team worked extensively on relocating the rider’s centre of gravity to a more efficient and safer place with the One, lowering it to compensate for shorter cranks and higher saddles, and moving it away from the front of the bike where it had ended up due to inline or negative-setback seatposts and ultra-long stems. “The centre of gravity of a complex shape can be really challenging, but it can be really simple as well,” he says. “It's super important in mountain bikes. Kind of never been talked about before on road bikes. You've got your moment arm and the centroid of your body mass. Determining a centroid of different areas has become a lot easier with computers… before you had to use calculus to do it.” Additionally, Shrive points out, a rider’s centre of gravity is dynamic rather than static. “You can see pros doing this intuitively. They move their shoulders down going into a corner, they sit up, slide back. But right now what’s happening with riders’ fit is that they’re getting outside the parameters of what they can adjust with their body. They’re moving outside of that operating window and they can’t compensate by moving around with the bike. They can’t get enough weight off the front wheel, so they’re crashing. Maybe the rear wheel becomes too light so they highside. That’s what we’re trying to give them back. We’re expanding that operating envelope to accommodate the new positions.
“There’s a lot of different competing aspects, but bringing it together you’ve got larger tyres, shorter cranks, more forward positions, evolving UCI rules. An amalgam of that experience compared with how the riders are using the bikes led us to try to get the best way to enable riders to do what they want to do anyway.”
Shrive’s solution was lower the bottom bracket drop by 5mm to compensate for raised centre of gravity due to shorter cranks (optimsed for 165-170mm) and larger tyres (28mm with a max clearance of 34mm). The handlebar mount was decoupled from the steering axis – ie a stem isn’t clamped to a steerer tube thanks to the ‘hinge’ design – enabling extreme reach without an over-long stem. Instead, stem sizes are designated one to five, corresponding with 110mm up to 150mm stem lengths in old money. The seat tube angle is pretty steep at 76 degrees in the three middle sizes out of five, though Factor illustrates that the effective fit matches that of the Ostro VAM despite the steeper nominal seat tube angle and says riders familiar with the Ostro VAM will find their core coordinates unchanged with the One. And finally, incredibly, toe overlap is eliminated even with the smaller sizes thanks to the forward-set fork and slightly longer wheelbase.
Manufacturing: too radical for outsourced production
Factor says that owning its own factory in Taiwan allowed it to build a structure no contract manufacturer could. It could rapidly prototype without waiting for third-party tooling cycles, it could tune carbon layups for stiffness and ride feel under extreme loads and could “engineer intelligent, user-friendly solutions to things like bar rotation limiters, Di2 battery integration and a low-profile UDH compatible interface”. In controlling every process from carbon cutting to curing to finishing, “we could move from CFD to tunnel to race without compromise or delay.”
The carbon fibre used is, according to Factor, a proprietary blend of Mitsubishi and Toray pre-preg including high-strength pitch fibres nano-loaded resins such as T1000 and T1100 as well as very high modulus pan fibres such as HR40 and M60J. A size 54 frame has a claimed weight of 900 grams.
Ride impressions
I had sent my bike fit measurements to Factor in advance of the media camp in Girona and a size 56 One had been set up accordingly. Of the two different seatposts available, mine had the equivalent 30mm setback version in it. The other is the zero setback post. There’s no doubt the zero setback version is the one that looks ‘right’ – so I asked Graham Shrive if the One’s geometry might be about to exclude riders with more traditional bike fits? “The modern power rider sits in a more aggressive position but we’re not trying to alienate the old school. However, if you have, for example, greater than 10 centimetres of setback you’re probably going to struggle to get your position on this bike.” My own setback, as determined by my last bike fit with Giuseppe Giannecchini, is 8.68cm so I’m just within the parameters but, as Shrive had already pointed out, the more traditional positions are not the norm any more.
At the front, however, my stem was reassuringly slammed. For more rise, dedicated wedge-like spacers can be added under the proprietary gull-wing cockpit, and for even more rise there’s a separate ‘hi-rize’ version.
“The hi-rize bar is frankly more of a concession to our own staff because Rob and I can’t ride totally slammed,” says Shrive. “So we thought, well, why not make something for ourselves and that comes in three sizes [stem lengths] compared to the five of the standard cockpit. There’s more decisions we’ve made consciously, like only quite narrow bars being offered [38mm] – we’ve gone down to what is now the current UCI minimum.”
Shrive says bikes will ship with the bar pre-chosen by the customer: “Our goal is to offer the whole size range of bars and seatposts with every frame as part of the purchasing process. Similarly with wheels, although it’s optimised for the 62mm rim depth.”
But is there a risk that people might not understand how to set up the One, which components to select? “Yeah, there’s a couple of different risks there. One is a communication risk – that you alienate riders because they don’t understand what you want them to do. Then there’s the actual application risk. We’ve gone to a longer wheelbase in the bigger sizes [1,002mm in the size 56] and people might think they won’t like the way that feels. Then in the smaller sizes we’ve gone to more aggressive handling, a steeper head tube angle. But we used the UCI prototype window to test it, we took our time with it and the reactions have been overwhelmingly positive, and that’s from the smaller riders on the Human Powered Health team to the larger riders on a 58, which is the biggest size.”
Finally, before we ride, I want to know about the pro riders’ reactions when they were first presented with the One. Shrive says: “At first it was kind of a head-scratcher. The geometry story is challenging to convey, but the message has been the same all the time: we’re trying to meet you where you’re at. We’re trying to empower you to make these changes that you want to make. In the end it was a very positive reaction. We worked particularly with two young riders, Jake Stewart and Riley Sheehan and they were both slightly confused by the geometry but very excited about the intention.”
There’s surprisingly little discussion about the aesthetics. Traditionalists, look away now. I found the One very easy on the eye – muscular yet sleek, avant garde yet practical. And the snow camo paintjob of my test bike, actually called Nimbus Grey, is a master (brush) stroke. I could happily live with it.
After a short shakedown, the first ride was, fittingly, a blast up and down Factor brand director David Millar’s old TT training road south of Girona – just longer than 10 miles – with Millar himself. I enjoy a road-bike TT and settled into an aero-hoods position on the front of our group for some threshold. Having spent a decent amount of time on the Factor Ostro VAM last year, I feel qualified to compare them, and my first sensation was – perhaps unsurprisingly – that the One felt stiffer, blunter and perhaps a little less refined. Obviously, it is also a little heavier. The Dura-Ace equipped Ostro VAM was on the 6.8kg UCI weight limit and was incredibly responsive, whippy, like a climbing bike disguised in aero tubes. However, when the One got up to TT speed, my impression was more of stability. It felt designed for sustained power pedalling in an aero tuck. In particular the front felt exactly as you’d imagine it would, with the bar almost directly over the head tube structure rather than out on the end of a longish stem. Super direct, zero flex but with 100% predictable steering, neither too twitchy nor too slow. Later in the afternoon we climbed to Santa Pellaia to get some photography, spinning up the easy gradient together but doing our own thing and letting loose on the way back down. At over 70kph the One felt completely planted – it was very impressive and felt perfectly weighted through the corners.
On the final day, I opted to take the One out for a last ride ride. Millar sent me the GPS for a 65km loop that went up the back of the classic Els Angels climb. This time, on a longer circuit with just one other rider, I was able to feel the One in more detail and listen to it. Literally listen to it – I don’t remember a bike that has sounded so satisfyingly fast with that muted roar of carbon, especially out of the saddle. When we came to the Els Angels climb and I dropped it into the little ring and swung it side to side it sounded even better. It didn’t feel slow either – obviously it’s not a climbing bike but the power transfer is so direct that with a really light build there would be no reason for a pro rider to choose a different bike – which is what Factor expects.
Then there was the enormous fun of descending fast on it – with a halt to let the Traka race hurtle across the road in front of us – back to Girona and a final tear-up along a main road, drag racing some local riders who had spotted our bikes.
Conclusion
So I got three consecutive days on the One, which is enough to venture a first impression. It seems to me that it’s the ultimate pro bike for 2025 onwards, now that Factor has both re-centred rider fit and made a bike that’s more aero than anything else out there. It is the most progressive, the gamechanger, the one to beat (if you'll excuse the pun). Would I buy it? If I was looking for pure performance and I was an elite racer, I would be crazy not to. But, as Shrive says, now that the geometry envelope has moved to normalise formerly extreme positions, the more traditional bike fits become the outliers. I wasn't keen on my saddle looking as if it was perched on the back of the seatpost and for me – as for most of us – everything has to be right. However, this was just the first ride, the bike was set up to my measurements that are a few years old now, and it's perfectly feasible that my position could be refined and improved in line with more current fitting concepts.
Applying the bigger picture, it's called progress. Progress depends on change and, according to the George Bernard Shaw quote, those who cannot change their minds cannot change anything. Perhaps he needed to include bike-fit positions in that.
Shrive is determined to keep driving the change – the final word comes from him: “The very interesting thing for me is to see if in the coming season we see riders radically alter their positions. So far this season we’ve seen the test riders mirror their previous position, but this is what we feel strongly is just the start. Biomechanically and physiologically it’s opening the door for them to continue this evolution of fit. There's a lot of excitement that it expands the envelope.”
The Factor One will be available in four builds, all with Black Inc 62 wheels, starting with Shimano Ultegra Di2 at £10,899 up to the flagship SRAM Red version at £12,899. There are five sizes – 47, 52, 54, 56, 58 – and four colour options: Blush, Nimbus Grey, Onyx Black and Silverstone. Go to Factor's website for all the details.
