Factor officially unveils all-new One aero bike, declaring it “the fastest UCI-legal road bike in the world”

The Factor One is the bike that sparked something of a media storm when it was first spotted at the Critérium du Dauphiné (above), where Israel–Premier Tech’s Jake Stewart rode it to victory on the fifth stage – although we didn’t have a model name at the time. Factor launched the original One for the 2016 season, with an update in 2018. The most notable features of the new model are the super-wide fork and seatstays, plus a new V-shaped cockpit.

Jake Stewart apparently reported: “Holy shit, when it hits 50kph it really starts to fly.”

So what are we getting here? As you’d guess, Factor is talking all about speed.

Having already seen an unreleased Cervélo S5 and some new wheels from Specialized prior to stage 1 of the Dauphiné, we arrived on a large car park in the French commune of Domérat for the race départ expecting a fairly run-of-the-mill morning: grabbing as many photos of pro riders and their bikes as possible to use throughout the 2025 season, heading back into town for a coffee and croissant, then going to watch the finish.

We hadn’t had the slightest hint of a tip-off that Jake Stewart was hiding a radical prototype aero bike on the Israel–Premier Tech team bus, and when he carried it out, we happened to be in the right place at the right time to start snapping and telling social media about it within minutes. Stewart himself and the IPT staff were coy but played the game well, obviously anticipating there would be some attention around the new bike, and giving us just enough time to get plenty of pics before he spun away to the start line.

In what was a tumultuous and controversial season for IPT that ultimately led to the team’s complete rebranding and a change of nationality, the story surrounding this bike reveal will be something Stewart and his colleagues can look back on fondly.

Jack Sexty, road.cc editor

“The Factor One represents a shift in how modern race bikes are conceived,” it says. “Elite racing has evolved: riders sit further forward, run narrower bars, shorter cranks, deeper tyre volumes, and more aerodynamic positions than ever before. The One was engineered around these realities from day one, not retrofitted to them.”

As you’d also guess, the fork is a big part of the story.

“The defining feature of the One is its bayonet fork and ‘chin’ fairing system, a structure made possible by recent UCI rule changes and shaped through hundreds of CFD [computational fluid dynamics software] iterations,” says Factor.

Chin? It’s that forward-projected structure at the front of the fork, logically enough.

“It controls airflow at the very start of the bike, minimising spillover drag and sustaining advantage deep into yaw where other platforms lose efficiency,” says Factor.

> Find out more about UCI equipment changes here: Why the aero road bike is making a comeback 

“Every variable was run through CFD with both half-frame accelerated models and full rider configurations before entering the tunnel in Canada. We confirmed the numbers: the wide fork with ducted chin produced the lowest drag and the most stable yaw performance, holding its advantage beyond 15° where competitors fell apart. The One’s front-end design isn’t simply about cutting the air — it dictates where the air goes next, ensuring smoother flow across the entire system.”

Essentially, Factor is saying that many rival bikes begin to stall rapidly at higher yaws: drag increases steeply as the flow becomes detached from the frame (and accompanying sections), so rather than acting as a sail and generating thrust, these sections create pressure differentials, spending energy and creating drag.

“One not only bests all available bicycles at low yaw thanks to its incredibly small frontal area, but both its aero cross sections as well as the transitions between these sections have been carefully designed and managed to ensure the airflow stays attached for as long as possible, adding a net thrust at yaw, and managing the vortex shedding of the airfoils to decrease the drag generated by downstream members such as the rider’s arms and legs,” says Factor.

“The One’s headline drag reduction is the sum of cumulative micro-optimisations validated independently and in system-level testing:

• Bayonet fork + chin fairing: Eliminated tyre spillover turbulence.
• Brake mount angle optimisation: Reduced interference drag by measurable margins by influencing downstream airflow.
• Bar top profile: Neutral section selected for aero gain + handling stability.
• Cockpit sizing system: Rider position optimisation without stem-induced instability.
• Centre of gravity control: Improved high-speed handling, preserving aero posture in cornering and sprints.”

Factor says that the One’s aerodynamic advantage has been validated in wind-tunnel testing at Guelph (Canada) and SASI (South Australian Sports Institute). 

As mentioned up top, it says that the new One is more than 8% faster than the Ostro VAM 2.0 and over 22% faster than the Specialized Tarmac SL8. Although we don’t have the conditions of the testing, Factor usually bases its road bike stats on 48km/h (30mph), and averaging of results at yaw angles up to 15° on both sides of the bike.

There’s tons of debate about the best way to go about wind tunnel testing and the most realistic/informative way to present results. Factor says the largest performance gap over the Specialized Tarmac SL8 was at 10°–15° yaw – although we’re often told that we spend the vast majority of our riding time at lower yaw angles than that in the real world.

Factor also says that the One is approximately 15% faster than the 2024 Cervélo S5, although Cervélo did unveil a new S5 last year.

> Cervelo says new S5 is “at least 5 watts faster than the bikes of our competitors” 

Factor says that the One “maintains aero advantage beyond 15° yaw, where competing platforms lose efficiency” – although, as the brand has highlighted in the past, experiencing yaws of this angle while riding is pretty rare.

Factor has also done a lot of work on geometry with the aim of enabling modern racing positions without destabilising handling or confidence. We all know the trends over the past few years: saddles are moving forward, cranks are getting shorter, bars are getting narrower, cockpits are getting longer to extend reach…

“These changes push the rider’s weight further forward, raising the centre of gravity and unbalancing the front/rear load split, a recipe for reduced stability and increased crash risk,” says Factor.

“[Our] engineering team embraced the reality that today’s riders are pushing fit boundaries once considered extreme. By decoupling the handlebar mount from the steering axis, the One enables reach positions that would previously require unstable stems.

“By building cockpit sizing into the integrated bar system, the One eliminates the compromise of ultra-long stems while giving modern racers the forward position they demand, with stability and control preserved. The stiffness levels of the Gull wing bar are extraordinary: as much as 50% higher than an equivalent bar/stem combo.”

The new integrated bar system removes the stem, replacing it with a selection of five sizes (the equivalent of 110–150mm stem lengths), three rise options, and up to 15mm of spacer adjustability. With the spacers and the bar rises, you have a total front end height adjustability of 35mm “without sacrificing aerodynamics or handling”.

“A revised bottom-bracket drop restores handling balance altered by shorter cranks and modern tyre choices, keeping the bike planted at high speed,” says Factor.

The bottom bracket drop is 77mm on sizes 47 and 52, and 75mm on the larger sizes. That compares with a bottom bracket drop of 72mm and 70mm on Factor’s current Ostro VAM.

The idea is that the bike feels planted on high-speed descents. Riders fitting shorter cranks typically raise the saddle to compensate. The idea of dropping the bottom bracket is that it keeps your centre of gravity in the same place after this change has been made. The geometry is optimised for 165-170mm cranks.

What’s the One’s weight? Factor claims 900g for a frame (size 54), and 540g for the fork. That’s a little more than other forks at this level, but it’s hardly surprising given the leg and bayonet steerer profiles. The cockpit (size three of five) is 210g, and the seatpost is 230g.

Tyre clearance is given as 34mm (measured) or 28mm (nominal), based on a 28mm tyre fitted to a rim with a 23mm internal width.

The Factor One comes in five sizes (47, 52, 54, 56, 58) the four colour options (Blush, Nimbus Grey, Onyx Black, and Silverstone). 

 

The adjustable seatpost head gives a virtual seat tube angle of 73.5-77°.

Factor says, “[The One offers] effective fit parity with the Ostro VAM – riders familiar with our flagship aero race bike will find their core coordinates unchanged, despite the One’s steeper seat tube angle.”

Graham Shrive, Factor’s chief engineer – previously at Cervélo – said, “This is the best bike I’ve ever made, and I believe the best bike produced in the road industry so far. The reason is clarity of purpose. No one questioned the mission: build a bike to help riders win races.”

Factor One prices

You can buy a Factor One Premium Package (frame, fork, cockpit, seatpost) for £6,899. It’s compatible with electronic shifting only.

Complete bikes come with Black Inc Sixty Two Wheels. The One is available with Shimano Ultegra (£10,899) and Dura-Ace (£12,599) groupsets, and with SRAM Force (£11,099) and SRAM Red (£12,899) groupsets. The SRAM models are fitted with power meters.

factorbikes.com