Factor officially announces the Ostro, a ‘super-light aero race bike’ with new carbon wheels

Described as a ‘quiver killer’ bike, Factor says it’s as good on cobbles as it is in the mountains

Factor Ostro

Factor has officially announced its new all-round, lightweight aero bike, the Ostro.

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Recently spotted by BikeRadar at the Criterium du Dauphine, the bike has since been used by Israel Start-Up Nation team riders during the first week of the 2020 Tour de France.

As we speculated originally, the Ostro incorporates features from Factor’s One aero road bike and its O2 VAM lightweight climbing bike, to make one all-round bike that Factor says is ‘ready to win sprints, mountain stages and cobbled Classics’.

Alongside the new Ostro frameset, Factor has also announced a new set of Black Inc wheels, the Black Inc Forty Five. Like the Ostro, Factor says this new tubeless-ready wheelset is optimised to be both lightweight and aerodynamic.

No compromises

Continuing a big trend for 2020, the Ostro sees lightweight and aero bike features converge into a singular package.

Graham Shrive, Factor’s director of engineering, explains its sponsored professionals have always asked for an aero bike with no weight penalty (or a lightweight bike with no aerodynamic compromises, to put it another way), as well as an aero bike that’s comfortable enough for the cobbles of Paris-Roubaix and similar races

So, instead of trying to build specific bikes for each situation (as Factor has done previously), Shrive says Factor has focussed on making one bike that can do it all.

Factor Ostro
The Factor Ostro is already being used by Israel Start-Up Nation at the Tour de France, with climbers like Dan Martin riding it during the mountainous first week.
Jered and Ashley Gruber

Factor Ostro key features

  • Claimed 780g frame weight (size 54cm, Flicker paint job)
  • Truncated aerofoil tubing throughout
  • A wide stance fork that is aerodynamically optimised for 26mm tyres but has clearance for 32mm tyres
  • A seatpost and rear end tuned for comfort 
  • ‘Weight neutral’ fully internal cable routing
  • Electronic shifting and disc brake only
  • T47 threaded bottom bracket
  • Identical geometry to the Factor O2 and O2 VAM

It’s lightweight

Key to the Ostro’s lightweight credentials is its claimed 780g frame weight for a size 54cm, with the Flicker paint job (which is essentially a clear coat over carbon with painted graphics).

That’s 20g lighter than the new Specialized S-Works Tarmac SL7 frame (though given these things are always subject to small error margins, we’d say that’s about even), and only a hundred grams or so heavier than Factor’s own, recently updated O2 VAM lightweight climbing bike.

Factor Ostro
The Flicker paint job is the lightest Factor offers. The carbon structure of the bike can be seen under the clear coat lacquer.

Trek’s new lightweight aero bike, the Emonda SLR is apparently capable of hitting sub-700g figures for an unpainted frame, but Trek doesn’t specify what size that applies to, so it’s slightly harder to make comparisons.

Whoever truly wins in the lightweight-disc-only-aero-bike wars, Factor says the key thing is that the Ostro can ‘easily’ be built to the weight limit of 6.8kg for bikes used in UCI-sanctioned events, even when equipped with a power meter and its new mid-depth Black Inc Forty Five wheels.

…and aero

As expected, the Ostro doesn’t use the wild, split-downtube design seen on Factor’s One aero bike, and instead uses more traditional truncated aerofoil tubes throughout the frame.

Originally seen on Trek’s Speed Concept time trial bike way back in 2009 (Trek called them ‘Kamm tail’ virtual aerofoils), the theory is that they trick the airflow into acting like there is a much deeper aerofoil present, yet allow bike designers to stay within the UCI’s strict regulations of bicycle tube shapes and sizes.

Factor Ostro
The Factor Ostro has a wide, truncated aerofoil shaped downtube.

The truncated aerofoil tube shapes also tend to display much better stiffness and weight characteristics than more traditional aerofoil shapes, as they have larger cross sections. Because of this they’ve since become de rigueur on road bikes that want to be both lightweight and aero.

This design convergence has led to a certain amount of negative commentary in recent years though, with many lamenting that ‘all bikes look the same these days’.

Generally, blame for this has been laid at the UCI’s door, but radical designs like the Hope/Lotus HB.T track bike and Factor’s own One aero road bike, have shown that there is still significant room for individuality in bike design, even within the UCI’s design regulations.

More integration and don’t forget about comfort

Helping it’s aero credentials, the Ostro also takes advantage of a fully integrated handlebar system, which means cables are routed completely internally (instead of being exposed to the wind), although a non-integrated handlebar and stem can also be used (with cables routing under the stem).

Factor says its integrated system is weight neutral – meaning it doesn’t add any weight compared to an externally routed cabling system – but it is only compatible with electronic drivetrain systems, such as Shimano Di2, SRAM eTap or Campagnolo EPS.

Factor Ostro
The integrated handlebar routes all cables internally into the frame, to hide them from the wind.

As mentioned, the fork has a wide stance design that is said to reduce the turbulence caused by the rotation of the spokes in the front wheel, and also allows clearance for up to 32mm tyres on wheels with a 21mm internal rim width.

This extra tyre clearance, combined with the Ostro’s new seatpost and thin dropped seat stays, are what Factor says make it an aero bike capable of taking on the cobbled classics too.

A race like Paris-Roubaix is 260km long and is ridden at an average speed of around 45kph, so aerodynamics will account for a lot of energy expenditure over the course of that race.

The fork also has what Factor calls a ‘reversing flow energising channel’. This is a channel built into the underside of the fork crown, which is said to decrease aerodynamic drag in that area by relieving the pressure build up due to ‘stagnant airflow’ created by the front wheel.

Home mechanics may also be happy to know the Ostro has a T47 threaded bottom bracket, which is essentially a super-sized version of a traditional threaded bottom bracket.

There’s much to like about this bottom bracket standard, especially from a user-serviceability point of view, but we’ve also previously argued that it’s a solution to a problem that shouldn’t exist.

Factor Ostro
The Ostro has a T47 threaded bottom bracket and clearance for up 32mm tyres.

Factor Ostro builds and prices

The Factor Ostro is available to pre-order now in two builds (with SRAM eTap wireless drivetrains) or as a frameset, in three different paint jobs; Flicker, Soho Mix & Sicilian Peach.

Factor Ostro with SRAM Red eTap AXS

Factor Ostro SRAM Red eTap AXS
The Ostro with SRAM Red eTap AXS is, as you’d expect, the more expensive of the two builds.
  • Frameset: Factor Ostro
  • Groupset: SRAM Red eTap AXS
  • Wheels: Black Inc Forty Five
  • Finishing kit: Black Inc integrated handlebar and seatpost, CeramicSpeed bottom bracket
  • Price: £9,250 / $10,099

Factor Ostro with SRAM Force eTap AXS

Factor Ostro SRAM Force eTap AXS
This build with SRAM Force eTap AXS uses the same frameset, wheels and finishing kit as the top-of-the-range build.
  • Frameset: Factor Ostro
  • Groupset: SRAM Force eTap AXS
  • Wheels: Black Inc Forty Five
  • Finishing kit: Black Inc integrated handlebar and seatpost, CeramicSpeed bottom bracket
  • Price: £7,850 / $8,199

Factor Ostro frameset

Factor Ostro Frameset
The Ostro is also available as a frameset, which includes the frame, fork, integrated handlebar, seatpost and CeramicSpeed bottom bracket.
  • Frameset: Factor Ostro
  • Finishing kit: Black Inc integrated handlebar and seatpost, CeramicSpeed bottom bracket
  • Price: £5,400 / $5,499

New Black Inc Forty Five wheels

Alongside the Ostro, Factor has also announced a new set of wheels, the Black Inc Forty Five.

Tubeless-ready and disc brake only, the new Forty Five wheels by Factor’s sister company Black Inc feature 45mm-deep carbon rims, with an internal rim width of 20.7mm and an external rim width of 27mm.

According to Factor, this means the wheelset is optimised for 25-28mm tyres, with a 26.4mm Maxxis tyre (inflated width) being the ‘perfect’ size, aerodynamically.

Black Inc Forty Five wheels
The Black Inc Forty Five wheels are optimised for yaw angles below 10 degrees, as Factor says these are what riders actually experience most of the time.

The wheels have 24 spokes front and rear, and the Black Inc HU-07 hubs run on CeramicSpeed bearings.

Based on the NACA 0018 aerofoil shape, the Forty Five wheels have been designed primarily around what Factor describes as ‘real-world conditions’.

Experiencing yaw angles (the angle of attack of the wind on a cyclist) above 10 degrees while riding is, according to Factor’s research, ‘very rare and not a use case for which performance in other conditions should be compromised’.

Given this, Factor says the wheelset has optimised for yaw angles of 0-10 degrees.

The Black Inc Forty Five wheels are available to pre-order now, at an RRP of £2,170 / $2,349.

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