Factor One review: A member-exclusive deep dive into the most talked-about aero bike of the year

The Factor One has to be one of the most talked-about bikes to launch in years.

It first broke cover at the Criterium du Dauphiné in 2025, and very quickly broke our small corner of the internet with its wild time-trial-esque design, extremely wide fork and chainstays, and bayonet fork with razor-thin leading edge.

Less than a day later, it looked as though it was going to be banned by the UCI, who announced a rule governing how wide forks and chainstays could be, but I later learned that Factor knew about the impending rule change and designed the bike right up to the legal limit.

It won a stage of the Dauphiné a few days later, and was then raced at the subsequent Tour de France by Israel-Premier Tech. And to cap it off, a pre-production prototype tested extremely well in the Cyclingnews aero bikes wind tunnel test, both with and without a rider, as you'll see in more detail below.

Soon after, it launched officially with an emphasis on its progressive geometry. In fact, the only thing bigger than the fork clearance was head engineer Graham Shrive's presentation on that matter. I'll get into that later, but in simple terms the bike is designed with a modern racing position in mind; further forward, with shorter cranks, narrower bars and bigger tyres.

It also launched with claims of being faster than the Tarmac SL8 – which our own testing data agrees with but Specialized's does not – and at a price that is sure to make most wallets wince.

In the UK, a frameset (with handlebar and seatpost) is £6,920, and full builds start at £11,056 (Shimano Ultegra). 'Standard' builds top out at £13,419.00 with Campagnolo Super Record.

I was sent the model equipped with SRAM Red to review (with power meter), priced at £13,082. However, it also came with the £506 optional extra CeramicSpeed OSPW system, as well as the not-currently-specced Black Inc 62 Hyper wheels, which alone fetch £3,799 (£1000 more than the 'standard' Sixty Two wheels).

To my maths, that makes this build £14,588 (or £1,000 less with the 'standard' Sixty Two wheels).

Design and aesthetics

To begin this section, it's pertinent to revisit the motivations that drove its creation. For years, Head Engineer Graham Shrive had wanted to design a bike that really pushed the envelope, but the brand's founder – then CEO – Rob Gitelis didn't think the Factor brand was ready to put something like this out into the world.

Through its sponsorship of the Australian Olympic Squad, the development of the Hanzo Track saw them unearth plenty of aero gains. Then the UCI's rules changed in 2023 governing how the fork and down tube could be designed together. In 2024, our original round of aero bike testing proved that the Ostro VAM was not only competitive but a leader in the 'superbike' space both in terms of weight and aero. With all those things combined, Gitelis decided it was time.

Concurrently, the brand was a sponsor of the Israel-Premier Tech team, who, like the rest of the pro peloton, were slowly shifting their positions to this modern consensus. Saddles were being slammed forwards to get over the bottom bracket and rotate the body to lower the front end, shorter cranks were fitted to keep the hip angle open, longer stems swapped in to accommodate the newly shortened reach, narrower bars added for aerodynamics, and tyre sizes grew for comfort, grip and rolling resistance improvements.

Shrive says this led to riders running stems that were so long that they were unsafe, and it put their centre of gravity too high and too far forward on the bike, meaning any sudden braking came with an increased risk of an over-the-bars crash.

Therefore, he designed the ONE's geometry with this in mind, and the result is that across all sizes, the reach of the bike has grown by 20mm. In my size 58cm, that means a reach of 421mm, which is 19mm longer than an equivalent Tarmac SL9, which I have also been testing.

To offset the fit implications of the longer reach, the seat tube angle is now steeper. On all but the 47cm frame (where it's 1°), the seat tube is now 2° steeper than the OSTRO, at 75.5°. Some basic trigonometry tells me that at my saddle height (785mm), that puts me 27mm further forward, easily offsetting the extra reach.

At the rear, the chainstay lengths are unchanged, so the distance from the bottom bracket to the rear hub is still 405mm (except the 58cm, where it's 408mm). This is shorter than most of the competition, and lends itself to an agile ride, albeit there's nuance to this in the bigger sizes that I'll get to shortly.

To account for the trend towards bigger tyres (and to a point, shorter cranks), the bottom bracket drop is now 5mm bigger (thus it sits lower) on all sizes.

The rest of the differences against the OSTRO VAM are size dependent. To account for handling goals and toe overlap concerns at the smaller end of the size run, Factor has kept a similar wheelbase to the OSTRO VAM (technically it's 3 - 4mm longer), steepened the head tube angle, and offset this by reducing the fork rake (in the 47cm frame, Factor has changed the fork rake by a quite significant 9mm).

The goal of this is that toe clearance (or the removal of toe overlap) isn't solely achieved by slackening the head tube angle so much that it ruins handling. As such, smaller riders should get a bike that handles as well as bigger riders. I've been riding a 58cm so can't verify it, but the logic holds.

To compare that again to the Tarmac – the Specialized doesn't come in a 47, so I'll compare the 52cm frames – the head tube angle is 73.3° on the ONE, 0.8° steeper than the 72.5° of the Tarmac. However, both have 58mm of trail because the Tarmac's fork has a 4mm greater rake (aka offset).

All that is to say, this should make the handling of the ONE slightly sharper than an equivalent Tarmac, especially combined with 5mm shorter chainstays and a 1mm shorter wheelbase.

At the other end of the size run, though, the increased reach has mostly carried over into the wheelbase. It's now 16mm longer than the Ostro VAM in the 56 and 58cm frames (which I have here). That makes it more stable, but it does lose some of that agility that made the OSTRO VAM frame special.

To continue the Tarmac comparisons, the One is longer and lower (19mm more reach and 4mm lower stack in my size 58cm). The Tarmac's head tube is marginally steeper, with a shorter trail, meaning the front end feels a little more nimble, which is no doubt also aided by the Tarmac's lighter weight.

But added to this, the Tarmac's chainstays are only 2mm longer (again, we're comparing the 58cm frame), and the wheelbase is 16mm shorter. In tight corners, this definitely bears out in the Tarmac's favour, but the ONE makes up the ground in other places.

Rounding off this comparison, since the Tarmac comes specced with a -15mm offset seatpost (you can change it) and the ONE comes with a straight post (you can also change this), I can get 42mm further forward on the ONE, which makes for a big difference in how I feel when I actually ride the bike. I can obviously also slide the saddle back to undo this, and as I'll explain below, I tried a few different positions.

Before I get into that, though, let's just talk about some of the other standout design points, because aside from all these geometry shifts, there's some serious engineering going on here.

Primarily, that's the way the front of the bike is put together. It uses a bayonet-style head tube (where the steerer tube doesn't travel through the head tube, but rather in front of it and clamps top and bottom); a design popularised by the Cervélo S5 and also now found on the Colnago Y1Rs, but the leading edge of the ONE is insanely narrow, even by the aforementioned bikes' standards.

The way the fork mounts into place is a little complicated, to the point that Factor has a 'V2' in its manual that simplifies the original instructions.

Thankfully for the mechanics out there, no specialist tools are needed (unless you count a hollow socket, but a ring spanner works in its place).

There's a rather large 'tension rod' that sits vertically and is tightened from the bottom to first add preload and also hold everything together. In my time with the bike, I experienced a loss of preload on multiple occasions, creating that unnerving feeling of a loose headset.

Loosening and re-tightening to add preload got me through the few months I had with the bike, but not without the final attempt shearing off part of the head of the bolt, meaning I was then unable to disassemble it for a proper fix. I'm well aware a paying customer would just take it back to a shop for a fix here, probably when the headset loosened the first time, and so a proper disassembly-reassembly would likely remove this issue entirely.

Where the ONE really changes the script, however, is where the cockpit clamps into place. Instead of mounting at the point of the steering axis, it clamps into place approximately 4cm further forward, downwards onto the top of the fork using four bolts (which are later hidden by a carbon cover).

The steering axis, and thus the 'lever' you turn when steering the bike, is still normal, so handling feels familiar, but this design means less distance between your hands and where the cockpit meets the bike, which makes it much stiffer. This adds to the directness of the steering, but it has pretty dire implications for comfort, as I'll get into later.

The rear brake hose (and Di2 cables where necessary, but my bike was wireless) routes vertically out of the top of the head tube, and is then directed around a tight corner forwards into a hole at the rear of the one-piece cockpit, before being directed left or right depending on which way round you run your brakes. The front brake hose travels entirely through the fork, and thus exits slightly further forward before being bent around another tight corner to the opposite lever.

Both of these are pretty difficult manoeuvres. That much was already clear from the state of the hoses in my test bike – they'd clearly been ravaged by pliers or mole grips to force them where they needed to go.

I got a taste of doing it myself when I needed to swap the bars from the size 1 (90mm stem / 110mm effective length) the bike was accidentally shipped with, to the size 3 (110mm stem / 130mm effective length) I needed, and pliers really are the only way to get the hoses to bend where they need to go. I'm just glad we're no longer using cable-operated brakes, as this would be on par with the Venge Vias's infamous rim brakes.

The other big design story (both literally and figuratively) is the wide fork, and despite having thousands of words on geometry already, there's actually not a huge amount to say.

Somewhat obviously, they draw from learnings made in the Hanzo Time Trial and Track development. Specifically, learnings about tyre wake and how the disrupted airflow acts downstream, and how the fork leg spacing helps to smooth the airflow before it then goes on to hit the frame and rider's legs.

Factor says it tested multiple fork leg spacing iterations to see which was fastest, and settled on a fork that is 114mm at its widest point; a mere millimetre under the UCI limit of 115mm.

The crown of the fork protrudes forward from the head tube to the point that it creates a little shelf. I could probably sit a small mascot on here like truck drivers who tie toys to their grill, but that would likely upset Shrive and the aero motivations for making it this way.

The depth of the fork blades no doubt aids the bike's ability to 'sail' in crosswinds, but what's less discussed is that Shrive intentionally changed the shape so that the leading edge was more vertical, because that makes it more perpendicular to the airflow. Most forks sit at an angle loosely in line with the head tube angle plus a little bit of offset, but the ONE's fork actually kicks forward at the top before coming down more vertically toward the axle. This really changes the aesthetic of the bike – and I'm still not sure I'm over that – but from an aerodynamics standpoint, it reduces the (horrible phrase alert) 'wetted length', which is the length of material in contact with the air, and improves the effectiveness of what is.

Performance

Clearly, a lot is going on with the design of this bike, and there's a hell of a price tag to boot, but how does it actually feel to ride, as a bicycle, on the road?

Well, the biggest surprise to me when I first hopped onto one is that it felt… normal. Save for a headset issue on my first test bike, which essentially gave it indexed steering, the Factor One rides and handles a lot like any other race bike.

The primary affectors of how the bike rides – its geometry, its material, its touchpoints – are all fairly normal. I've already spent 1000+ words on the geometry so I won't go there again, but aside from a seat tube angle that puts you further forward on the bike, and a wheelbase that's longer, everything else is pretty much the same.

The forward-protruding fork makes the head tube angle look steep, but in this size, it's the same as the OSTRO and 0.2° different from the Tarmac. The trail is similar, the chainstay length is similar, the stack is similar.

So if you came here to learn if riding the Factor One was going to feel foreign compared to your current race bike, there's a good chance that it won't (assuming that race bike isn't from the 1970s).

However, before you rush off to remortgage your house, 'normal' doesn't automatically make it great. In fact, despite the price tag, there are a lot of things the Factor ONE doesn't do very well. Whether that actually matters to you will depend on what you want from it.

If you're considering the Factor One as your only bike, I think you'll grow weary very quickly. To peddle a metaphor, it's akin to having a car designed for track meets as your daily commuter, or to borrow one from my colleague Will, using a fish filleting knife as your general-purpose knife. I will cut up a pizza, but it won't be the best tool for that job.

The primary reason for this is that it's ridiculously stiff. I'd love to put some numbers to this, but Factor chose not to be involved in our road bike stiffness tests earlier this year, so I'm left to infer from feeling. And the main 'feeling' is a lack thereof, because every time I ride it for more than about 40 minutes, my hands go numb. This is probably partly due to my weight being further forward and thus more supported by my hands, but there's no getting around how insanely stiff the bike - and specifically the cockpit - is.

In my entire history of riding other bikes, I can recall one instance of hitting a bump and my hands coming off the bars, causing me to almost crash. It's happened three times on this bike. I don't think that's a lack of attention on my part either; the jolt through the front end of the bike is so much more severe than I'm used to that smaller bumps that I'm otherwise happy to ride over are enough to dislodge my hands.

I've ridden the One with two different wheelsets (the 'normal' Sixty Two and the Hyper Sixty Two), two cockpits (110 and 130mm), with the Black Inc stock bar tape, without bar tape at all (through necessity for one ride) and with Fizik's Comfortfeel 3.5mm tape. The stiffness or numbness hasn't abated in any case.

Of course, I'm framing it as a problem, and it must be said that the One can accept 32mm tyres, but that stiffness has its benefits too. Yanking on the bars in an ugly-face, all-out sprint, the difference is night and day compared to pretty much anything else out there. Have you ever picked up an old smartphone and wondered how the hell you ever lived with it? That's kind of how I feel when I try to sprint on anything else now. The responsiveness in the pedals feels marginally better, but the feeling through the bars is ridiculously good.

It carries over into climbing too. The Factor ONE weighs 8.2kg in this setup (with pedals and computer, no bottles) but has the sprightly feel you get on a 6kg lightweight bike because of how the stiffness translates to the road. I doubt for a second it's actually undoing the 1.5kg deficit it has to the O2 VAM when it comes to a hill climb, but from a pure sensations point of view, it's a nice thing to have on a bike that can also then barrel along a flat road with ease.

And 'barrel along' it can. The ONE is a bike that enables the en vogue modern, progressive aero position, and for that I really like it. Partly because it lets me open up my hip angle and prevent pinching of my hip flexors, which has long caused me discomfort, but also because I get to ride in that racy, forward, purposeful position that has long-ago been shown to be more aero.

I've always been quite quad dominant in my pedalling technique too, and I feel this lets me play to that strength. This is also the first test bike I've had in years where I've not had to slam the saddle as far forward on the rails as it'll go, and I buy into the notion that a longer front-centre reduces the over-the-bar risk, even if it's not something I've ever really worried about before.

The downsides to this position mean I now have more trouble with my neck, because rotating my body forwards means my neck has to compensate in the opposite direction if I'm still to see where I'm going. I had it especially badly on the Ridley Noah Fast 3, but I seem to be in the minority in having this problem, so I'll brush it aside as a me problem for now.

But this all leads to the ONE feeling really at home. I'm loath to say it 'feels' fast, because so many other factors could come into play on any given day and we have the wind tunnel data to prove that it is – keep reading for that – but it 'feels' happy. The longer wheelbase adds high-speed stability, and where I found the Ridley Noah was buffeted by the wind quite easily with its deep wheels and mega head tube, the Factor is stable and surefooted. The switch to the Hyper wheels adds a slight twitchiness to the front end by dint of its reduced weight, but with either wheelset fitted, the bike was quite content ticking along at speed, even when the going got a bit blustery. And once I'd put the longer-reach cockpit on, I could sit in a nice long, low, narrow position and tick at speed nicely.

When the going gets twisty, however, I can't help but shake the feeling that the handling is actually comparatively slow in comparison to the Ostro Vam, Tarmac SL8 and SL9. I'd add the Noah Fast 3.0 to that mix too, but the Noah Fast I've ridden was a smaller frame size, so it's not a perfectly apples-to-apples comparison - not least since the Ridley geo is even longer and lower than this, with a slacker seat tube angle.

The extremely stiff cockpit kind of helps to offset this and give the impression of precision, and it goes extremely well on fast, sweeping descents where the roads are smooth because the front triangle flex that can cause vagueness under high load – like you get on the Y1Rs – isn't an issue here. But on tighter corners and hairpins, I'd often miss the apex. Overall, I just struggled to develop the intuition for how the bike would handle like I could on the OSTRO VAM, or like I can on the SL9. This is exacerbated when the road surface gets a little rougher, as is common here in the UK, as every bump is felt through the hands, making steering inputs more difficult.

Of course, I'm splitting hairs here, but it sort of bears out in the geometry charts in my frame size too. I think riders on smaller frames will probably feel differently, because in that comparison against other race bikes, the ONE's gets a steeper head tube and pairs it with a short wheelbase, but in my size, it's a different proposition with a longer wheelbase and no meaningful change to head tube angle and trail. Thanks to the position change, there's perhaps a little too much weight through my hands too. It's not a dealbreaker though. As I say, I'm splitting hairs and comparing an elite bike against other elite bikes, and it's perhaps something that I could reduce by playing around with more tyre sizes, different cockpits shifting my weight balance around to find a sweet spot.

Aero performance - wind tunnel test data

Cyclingnews subscribers will already be familiar with this, but the ONE can lay claim to the title of being the fastest bike we've ever tested in the wind tunnel, both with and without a rider. That's against a cohort of over 30 high-end road race bikes, and includes pretty much all the big players from Specialized, Trek, Cannondale, Colnago, Cervelo and more.

The graph above shows the CdA (the measurement of how aerodynamic something is) at seven different wind angles, with 0° at the centre being a direct headwind, and a lower measurement being better or more aerodynamic.

The Factor One is highlighted, and it's clear that its aero credentials come to the fore as the wind angle increases.

Using the CdA from each of those wind angles and averaging them out, we then calculate the number of watts needed to overcome the aerodynamic drag of both the Factor One and dozens of other bikes that have been through the same test.

We use an old, basic bike as the comparison, and can see that the Factor One tops the list, saving 40.28 watts. Perhaps more usefully, it's two watts more aerodynamic (at 40km/h) than the next best bike.

With a rider on the bike, things shift a little, but the Factor is still within 0.04w of the top spot, which is well within the error margin of the test. In this test, it was 27.53W more aero than our baseline bike with a rider, and 7.9W more aero than the Tarmac SL8 (we're yet to test the SL9).

And in our third aero test, we swapped out the stock wheels for a 'control' wheel - the Enve SES 6.7.

This allows us to see how each bike compares with the exact same wheel-tyre combo, isolating the aero differences to the frame, fork, handlebar and so on.

In that test, we once again have Factor atop the tree with a sizeable step to the next best on test.

To read the full breakdown, head to our wind tunnel aero bikes shootout or our Factor One wind tunnel deep-dive.

Value

The price of this build is £14,588, or $15,788. Minus £1000 or $1100 for the 'standard' Black Inc Sixty Two wheelset.

That's £90 cheaper (or oddly, $288 more expensive) than a Colnago Y1Rs specced with the same groupset and a similar wheelset upgrade (Enve 4.5 SES wheels). But it's also £2,589 more than an off-the-peg S-Works Tarmac SL9.

To contextualise just how much money the Factor One will cost, here's a look at what else you could buy. You could buy a Tarmac SL8 Expert - Ultegra Di2 (£5,499), a Crux 5 Expert Force XPLR (£5999) and an Epic Hardtail (Comp, S-1000 AXS and Sid SL)

Alternatively, if you wanted a top-tier race product, you could buy a Canyon Aeroad CFR (£8029) and still have enough to buy that aforementioned brand new Crux 5.

Or to put another spin on it, if you're buying it because you want to get better at racing, you could buy that aforementioned Canyon Aeroad CFR, and then spend £300 a month on a support network of various coaches for 21 months to help you find significantly more than the few watts you're saving here.

Verdict

The Factor One is a singularly minded, out-and-out race bike, and for that type of riding it's really good, but it's an incredibly expensive tool for a specific purpose, not a versatile bike. It's the drywall screwdriver in the toolkit; brilliant at its job, and technically capable as an impact driver, but it'd soon get tiresome.

The handling might not feel quite as sharp as the OSTRO did, but it's still really fun to ride when you're trying to go fast. Racing, KOM hunting, or simply chasing your mates on it is a hoot, and the geometry allows that 'modern' position. It's longer, lower, but with a steepness to the seat tube that doesn't just stretch me out, instead letting me really get over the bottom bracket, drop my elbows and ride it hard.

As a result, it's a bike that holds pace on the flat as well as anything else out there, and the stiffness means sprinting is also better than anything else out there.

But the big takeaway is that it's so stiff that riding it every day becomes tiresome. Even after adding plush bar tape and swapping to my favourite saddle, I feel battered if I go for more than a couple of hours, not to mention my numb hands and pothole incidents.

As such, this is more a race tool than an everyday machine. And that throws up another issue in that it has such a divisive aesthetic that plenty of its potential buyers wouldn't actually feel comfortable turning up to their local race on one.

The ability to get into the modern position is really good. But the Noah Fast offers this too.

It's not a bike I'd overall recommend, unless for a very specific purpose.