The Factor Ostro is a gravel bike you can take crit racing

Factor has added a new gravel bike to its range, dubbed the Ostro Gravel. In doing so, the brand says it has created the world’s fastest gravel bike.

Created for gravel racing, the Ostro Gravel draws inspiration from the Ostro VAM, the brand’s aero road bike but with lower speed aerodynamics, fast handling and more focus on comfort.

The Ostro Gravel is the newest addition to Factor’s gravel offering, and comes two years after the launch of the LS. While the LS focuses on light weight and the Ostro Gravel on aerodynamic efficiency, Factor claims a weight of just 900g for a size 54 fully painted Ostro Gravel frame.

According to the brand, the bike has clearance for 45mm tires but has a specific geometry to minimize the possibility of low-speed wheel flop with certain tire sizes.

Factor says the Ostro Gravel is aimed at riders looking for a gravel race bike. Pro gravel racer Dylan Johnson rode the bike at Unbound 2022.

‘The reason that we created this new bike was because of our commitment to gravel and alternative racing,’ says Factor founder and CEO Rob Gitelis. ‘We have invested heavily in the technology to create what we believe to be the world’s fastest gravel bike.’

Prices start from £4,730 for a frameset kit (including seatpost, cockpit, CeramicSpeed ​​headset and bottom bracket) and go up to £9,380 for the power meter-equipped SRAM Red eTap AXS full build. Availability is expected from the end of September.

Made for speed

Factor says aerodynamics have been a key consideration in the Ostro Gravel’s design, unlike that of the LS, which focuses more on light weight.

According to Factor, its engineering has resulted in a fast, aero gravel bike with lower speed aero-efficient features when compared to the Ostro VAM.

‘For the LS we made assumptions that gravel speeds were low enough that we didn’t see a benefit in having an aero frame and we really prioritized lightweight instead,’ explains Graham Shrive, engineering director at Factor. ‘But working with riders we realized that in gravel races speed is creeping up and being aero is becoming a major factor.’

The brand says it has manipulated the behavior of airflow around the head tube before it can be disrupted by the rider and the bike itself, specifically looking at the laminar separation bubble in that area.

‘We focussed on the free stream flow, the areas which come in front of the rider and outside of the wheel, so the forks, the headtube and then the handlebar and seatpost,’ explains Shrive.

‘At lower velocities, the airflow will detach and at some point it reattaches, but if you can trick that airflow to separate earlier it can then reattach quicker and you get lower performance drag further downstream.’

The Ostro Gravel’s Black Inc cockpit – Black Inc being Factor’s components brand – has also been designed to support the frameset’s aero rationale.

Factor says it has been designed to maximize the free air stream flow available before the rider’s body fouls the air moving past the bike and the rider.

Factor says the cockpit can save up to 9 watts in comparison to a regular bar/stem setup, although it did not specify at which speed this saving would be achieved.

Racing geometry

Factor says the Ostro Gravel’s purpose of gravel racing is reflected in the bike’s aggressive yet comfortable geometry.

‘We stretched the top tube by about a centimeter to try and promote the slightly further back center of gravity that you want when you are going down a really steep hill on a gravel bike,’ explains Shrive. ‘So you lose that tendency to feel like you have been thrown over the front end of the bike.’

‘We also coupled that with a slightly steeper seat tube angle, which is a response to the phenomenon of most people being on a zero offset seat post.’

The Ostro head tube angle ranges from 71.2 to 72.3 across sizes. Factor says this is because it has prioritized the steepest head tube angle possible, whilst maintaining neutral trail values ​​across the range so it can work with 43mm gravel tires as well as 32mm slicks with no low-speed wheel flop.

All-rounder intentions

A notable element to the Factor Ostro Gravel is that it is intended to be a ‘cross over’ bike, when ridden outside of pure gravel racing.

Factor says that the handling geometry was selected to ensure road-like trail values ​​when used with narrower tires, such as 30mm to 35mm, as they have a smaller outside diameter that typically reduces trail.

The brand claims that the rear center length, higher stack, and slacker head tube angle contribute to all day comfort, meaning that the bike can be used for more than just racing.

‘We didn’t want to restrict riders going in either direction. If you are really keen, you could probably race this bike in a crit with a smaller tire. Our philosophy is very much to try not to exclude any riders,’ says Shrive.

Flexible gravel spec

The Ostro Gravel features a removable front derailleur mount with a paint-matched carbon chip which Factor says means that riders can choose a 1× setup and the bike will still look attractive.

The bike also has integrated hose routing, but uses the industry standard of 1-1/2 upper and lower bearings and a fork steerer that will fit conventional stems.

‘With the plethora of cockpit arrangements around for gravel we don’t want to constrain any rider, we want to open up the system to a wide variety of stems and bars,’ says Shrive.

Factor’s latest gravel bike has electronic shifting, clearance for 45mm tires and is disc brake only.

It also comes with the new Black Inc Thirty-Four wheels which are hookless, feature custom CeramicSpeed ​​bearings and have a 25mm internal width.

The Thirty-Four wheelset is Black Inc’s first off-road wheel and the brand says while it is primarily made for gravel it is also capable on the road with a 30mm or larger hookless-compatible tire.

The Ostro Gravel also has a T47A threaded bottom bracket and features a new two-bolt seatpost, which the brand says is a robust solution for gravel.

It has multiple attachment points for bags, boxes, tools, and bottles.

Factor Ostro Gravel prices and availability

The Ostro Gravel is available as a frameset kit (that includes seatpost, barstem, CeramicSpeed ​​bottom bracket and headset), a frameset kit with Black Inc Thirty-Four wheels, or as a complete bike in the following builds:

  • SRAM Force eTap AXS XPLR + power meter ($8,199 / €8,120 / £7,060)
  • SRAM Force eTap AXS ($8,599 / €8,520 / £7,400)
  • SRAM Force eTap AXS + power meter ($8,799 / €8,720 / £7,570)
  • SRAM Red eTap AXS XPLR + power meter ($9,799 / €9,710 / £8,430)
  • SRAM Red eTap AXS ($10,499 / €10,400 / £9,030)
  • SRAM Red eTap AXS + power meter ($10,899 / €10,800 / £9,380)

Color options include ‘Naked Grunge’ (black), White Grunge (white) and custom paint schemes too.

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