The new Factor Ostro: an aero bike for the cobbles?

It's ready to 'win sprints, mountain stages and cobbled Classics'

(Image credit: Jered-and-Ashley-Gruber)

Factor has released a brand new bike that promises to be a 'do it all' machine: a veritable one-stop-shop for riders looking for a rapid racer with all the comfort of a long-distance tourer.

The new Ostro, unveiled underneath Israel Start-Up Nation at the Tour de France, aims to combine optimised aerodynamics with comfort worthy of the cobbles.

It seems that 2020 is the year that frame manufacturers are beginning to cotton on that sometimes just having the 'fastest' bike isn't quite enough if it suffers from ride quality and comfort issues.

Merida paved the way with it's latest Reacto, and Specialized took aim at the one do-it-all machine wit the new Tarmac SL7. Pinarello has taken a similar approach for much longer.

Now Factor is getting in on the game with the Ostro. Named after a Mediterranean wind, Factor clearly believes the Ostro will be capable of blowing the competition away.

“The OSTRO concept was born from my long experience working with pro teams and riders, especially at Paris-Roubaix,” explains Graham Shrive, Factor’s Director of Engineering.

“Every year there would be a couple of riders who wanted to use their aero bikes to get that advantage, no matter how poorly suited they were to the cobbles. Plus, of course, pros have always wanted an aero bike with no weight penalty, or a super light bike with no drag penalty in the valleys, as the climbers might see it. Instead of battling to get them on a bike made for the cobbles, we decided to build them what they wanted, and it turns out to be a hell of a bike."

However, Factor isn't diluting things and 'de-tuning' its aero bike or 'aero-ising' it's climbing bike; Factor will continue to produce the aero specialist ONE and O2 VAM lightweight climbing bike. The Ostro is designed to sit alongside these two established models.

Comfortably aero. The new Factor Ostro in Soho Mix colours.

The Ostro has, like most modern bikes, three key aspects in which Factor has focussed on improving - aerodynamics, weight and comfort.

Ostro aerodynamics

Factor has focussed on three specifics to improve aerodynamic performance:  aero profile tube shapes, a wide stance fork with 'Reversing Flow Energising Channel' and an aero cockpit with fully integrated cabling. 

The tube profiles are derived from NACA (National Advisory Committee on Aeronautics) shapes, oriented along the waterline (horizontal) in line with airflow. Like most other frames, these shapes have been truncated to reduce weight and increase ride quality without compromising too much on aero benefits.

One of the things Factor has worked hard on is perfecting the tight radius at the transition or cut point, something that can be challenging to manufacture in carbon fibre. As Factor has its own manufacturing facility it has been able to use a more expensive and time-consuming process to achieve the optimum shape without passing on that cost to consumers.

NACA inspired airfoil shaping abounds.

The new wide stance fork features something Factor calls a 'Reversing Flow Energising Channel'. Both the channel and the fork’s wide stance address the aerodynamic challenge of incoming airflow meeting the ‘reversing flow’ of air carried by the wheel and tyre moving forwards through the fork. This reversed flow stagnates behind the fork and disturbs airflow around the outside of the fork onto the down tube.

To solve this, Factor designed a converging nozzle into the fork crown to accelerate the reversed flow out of this area, significantly reducing the pressure changes met by the relatively clean air travelling over the outside of the head tube and fork legs, and thereby improving laminar flow and cutting overall drag.

Additionally, by significantly increasing the width of the fork legs, the fork legs and the wheel rim are each able to operate in airflow that is undisturbed by the other, allowing the aero profiles to function at optimum efficiency. 

New wide-stance fork and Black Inc integrated bar and stem add to the slipperiness.

The final aero piece of the puzzle is the new one-piece, Black Inc Bar/stem. This reduces drag by meeting clean incoming airflow with a clean shape. Fully internal cabling bring further gains and Factor has achieved this while maintaining a 11⁄8” top headset bearing for optimised frontal area.

Ostro weight reduction

The Ostro is an aero disc-brake frame weighing in at just 780g (painted, size 54). According to Factor it easily builds to the UCI limit of 6.8kg, equipped with a power meter and mid-depth aero Black Inc Forty Five wheels.

The tube profiles were carefully developed to balance aerodynamics against weight. The down tube, for example, has almost exactly the same cross-section as that of the O2 VAM. Also shared are the 'exceptionally high grades' of carbon fibre material used and the industry-leading manufacturing techniques employed to get the very best from them, all made possible because Factor owns its factory and can pass considerable efficiencies to the customer.

Finally, the new integrated cabling system, which debuted recently on the revised O2 VAM, is weight neutral, which is to say it doesn’t add a single gram. 

Ostro comfort

Factor's strap line for the Ostro is it is "an aero race bike that’s ready for Paris-Roubaix".

"Why be aero for Roubaix? Simple. It’s a 260km race that averages around 45kph and ends with a sprint in a velodrome. Any energy saved can make the difference to victory, and over that distance, at that speed you can save a lot of energy". 

The OSTRO achieves its comfort in three key ways: tyre clearance, ultra-thin seat stays, and carbon fibre layup. 

Super thin stays aid compliance.

Tyre clearance of 32mm is, quite frankly, huge for an aero race bike. This clearance is enabled by the disc-brake-only design and wide stance fork. Specifically, the Ostro has ISO clearance for 32mm tyres mounted to rims of 21mm internal width 

At the rear, the ViSTA-style pencil seat stays are designed to absorb road noise and cushion bumps. Furthermore, they meet the seat tube at a dropped angle which encourages the seat tube and seatpost to cantilever around the seat cluster to create an effective amount of controlled ‘travel’ at the saddle. 

For the OSTRO, the carbon layup was continuously refined in order to achieve a high level of frame compliance without sacrificing any of the power transfer efficiency. 

Other features

  • Identical geometry to the O2 and O2 VAM - This is the optimum racing geometry for confident handling and that is unchanged by this bike’s broader role.
  • Electronic shifting only - In line with customer demand and enabling aero drag and weight savings, the Ostro is built exclusively for electronic shifting groupsets.
  • T47 threaded bottom bracket - Used for the first time in a Factor, the T47 standard ensures a secure fit and easy maintenance. 
  • Three different fork offsets - Ensures optimum handling characteristics across all frame sizes so that every customer has the best ride experience. 
  • New lightweight seatpost - Mid-depth profile seatpost balances weight and aero, available in 0 and 25mm offset options. 
  • Launches with Black Inc Forty Five wheelset - The new Black Inc Forty Five, at 45mm in depth is designed as the perfect pairing with the OSTRO. The Forty Five is designed with an optimal balance of aerodynamic performance and lightweight for riders who want a single wheelset to do everything from high mountain gran fondos to flat road races to long training days, and everything else in between. 

Sicilian Peach is the other standard colour scheme for the Ostro.

The Ostro is available to preorder now, UK: £5,400 for the frameset package which includes frame, fork, seatpost, integrated barstem, CeramicSpeed bottom bracket and headset. 

Complete bike with SRAM Red AXS & Black Inc Forty Five wheelset: £9,250. Complete bike with SRAM Force AXS & Black Inc Forty Five wheelset: £7,850. 

The Ostro will be available in three designs, Flicker, Soho Mix & Sicilian Peach. 

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James Bracey

James Bracey's career has seen him move from geography teacher, to MBR writer, to Cycling Weekly's senior tech writer and video presenter. He possesses an in-depth knowledge of bicycle mechanics, as well as bike fit and coaching qualifications. Bracey enjoys all manner of cycling, from road to gravel and mountain biking.