Bike of the Week | The Factor Ostro Gravel is designed for go-fast gravel racing

British brand’s latest aero-optimised gravel bike  

Factor Ostro Gravel against a graffiti background

Hot off the heels of its launch last month, the new Factor Ostro Gravel has arrived at BikeRadar HQ for testing.

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The Ostro Gravel is aimed squarely at gravel racing, featuring aero-optimised tubes to make it competitive at races such as Unbound.

Factor says the Ostro Gravel takes the “win-everywhere mentality” from the brand’s Ostro VAM road bike and, in keeping with that WorldTour-proven machine, has been “developed to dominate its category with incredible aero, superior handling, high stiffness and low weight”.

Bold claims indeed but, before we deliver our verdict in a review, let’s take a look at this decidedly premium build.

It’s all in the frame details…

The Ostro Gravel is Factor’s take on a gravel race bike.
Oscar Huckle / Our Media

Factor says the Ostro Gravel uses a blend of TeXtreme, Toray and Nippon Graphite carbon fibres – a blend that, according to the brand, balances lightweight with “a strengthened layup” for gravel riding.

The brand claims a 54cm frame in ‘Naked Grunge’ (a carbon weave finish with white graphics) weighs 900g. It’s only compatible with electronic groupsets.

The head tube is certainly distinctive.
Oscar Huckle / Our Media

Paired with Factor’s Ostro Wide Stance Fork, the head tube is particularly striking and, along with the cockpit, contributes to a claimed 9-watt drag reduction at the front end of the bike.

The fork and head tube junction are aero-profiled.
Oscar Huckle / Our Media

In terms of mounts, there’s the option for a bento box on the top tube, as well as mounts on the underside of the down tube near the bottom bracket junction for a third bottle or tool keg.

That’s it for mounting points. If you need to take more luggage with you, you’ll have to strap on bikepacking bags.

The seatstays are decidedly dropped.
Oscar Huckle / Our Media

Factor says the Ostro Gravel can accept up to 700c x 45mm gravel bike tyres.

That’s not as wide as the clearance on some gravel bikes, with progressive machines aimed at bikepacking or more extreme riding having space for tyres upwards of 700 x 50mm, though it reflects Factor’s intentions for the bike.

CeramicSpeed’s SLT headset bearings are claimed to be unkillable.
Oscar Huckle / Our Media

As you’d expect from the brand, the front end is integrated, complete with CeramicSpeed SLT headset bearings.

In theory, you shouldn’t need to worry about changing those and having to undo the brake lines.

The bottom bracket also comes from CeramicSpeed.
Oscar Huckle / Our Media

CeramicSpeed also supplies the bottom bracket, with a hint of blue on this otherwise stealthy machine.

The bottom bracket standard is T47A (T47 Asymmetrical), which uses the same threaded design as T47, only with the wider and oversized interface of BBRight.

Cervélo pioneered the BBRight standard and Factor was one of a few brands to also employ it. In terms of fitting your chosen crankset, the T47A means you’ll need to run a few spacers on the driveside.

What is Bike of the Week?

Every fortnight, we’ll bring you a detailed first look at one of the latest bikes (or framesets) to arrive at BikeRadar HQ – from road to commuting, gravel to enduro, and anything in between.

This is our chance to introduce the bike and everything that makes it unique before hitting the road or trails.

Head to our Bike of the Week hub for previous editions.

A tasty spec list

A premium build from a premium brand.
Oscar Huckle / Our Media

Our Factor Ostro Gravel, in its sparkly ‘Naked Grunge’ matte paint job, is specced with a SRAM Red eTap AXS XPLR groupset. There is also a ‘White Grunge’ paint scheme available.

It retails for £8,430 / €9,710 / $9,799 and the range starts from £7,060 / €8,120 / $8,199 for a SRAM Force eTap AXS XPLR build.

There is also a ‘premium package frameset’ option. This includes the frame, fork, bar/stem and a CeramicSpeed headset and bottom bracket, for £4,730 / €5,450 / $5,499.

It’s all top-of-the-range SRAM Red eTap AXS XPLR.
Oscar Huckle / Our Media

There are no deviations to the groupset on this halo build and our size medium sample features a 172.5mm crank length, a tall 44-tooth chainring and a 10-44t cassette.

This model comes equipped with a Black Inc Thirty-Four carbon wheelset, claimed to weigh in at 1,489g. The 34mm-deep rims, with a 25mm internal width, are built around Black Inc’s own hubs, which in turn feature CeramicSpeed bearings.

These Goodyear tyes should ‘connect’ you to the trail.
Oscar Huckle / Our Media

The wheels come set up tubeless out of the box with Goodyear Connector gravel tyres in a 700 x 40mm width – generally considered a sensible width for all-round gravel riding.

The finishing kit is also courtesy of Black Inc, with an integrated bar-stem wrapped in Factor’s own bar tape and, on our test bike, an out-front Garmin mount.

Our test bike has a 100mm stem length and 40cm bar width.
Oscar Huckle / Our Media

The HB02 carbon bar-stem features aero-profiled flattened tops and, on this 56cm test bike, has a 100mm stem length and 40cm bar width.

There’s a power meter, too.
Oscar Huckle / Our Media

The one-piece HB02 bar-stem is available in 20mm width increments (36cm to 44cm) and stem lengths starting from 80mm, up to 140mm.

However, if you want to run your preferred handlebar and stem combo, Factor says you are free to as the steerer tube is round.

A Selle Italia saddle sits atop Factor’s own seatpost.
Oscar Huckle / Our Media

A proprietary non-round aero seatpost slots into the seat tube and a Selle Italia Model X BB FEC with alloy rails saddle fits on top.

All-in, our 56cm bike weighs in at 8.12kg without pedals.

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We’re currently testing the Factor Ostro Gravel, so you can expect a full review on BikeRadar soon.