The 2023 Factor OSTRO Gravel makes no secret of the fact that it wants to be in the front row come race day. The aero features, dynamic look, and moderate weight are sure to give your competition a fright. Can it deliver in our gravel race bike group test or is it all bark and no bite?
This bike was reviewed as part of our 2023 gravel race bike shootout. You’ll find a comprehensive group test and test field overview here: Which is the best gravel race bike of 2023? 9 gravel race bikes in review
When designing a bike, the UK brand Factor Bikes always focus on speed. Racing is at the core for Factor and so is the search for marginal gains with the help of integration and aero optimisation. Of course, this is no different with the 2023 Factor OSTRO Gravel. It’s an all-new addition to their portfolio and shares a name with the road-oriented OSTRO VAM. With the 2023 OSTRO Gravel, Factor have taken a consistent approach to aero optimisation. Along with the BMC Kaius 01, it is the hottest contender for the gravel race bike throne. But how does it compare to the other purebred racing bikes, and can it meet our testers’ expectations?
What makes the 2023 Factor OSTRO Gravel special?
It looks fast just standing there! Factor weren’t stingy with aero features on the 2023 OSTRO Gravel, trying to outsmart wind resistance with various tricks. Starting with the seat post with its deep aerofoil profile and the aero-optimised frame and ending with the unique shape of the head tube. The latter has a narrow cross section and is tapered towards the centre, which promises to keep turbulence to a minimum. Deep tube profiles join forces to combat wind resistance, at least in theory. In summary, it all looks very streamlined and should provide the hoped-for marginal gains in practice. The gravel sibling looks quite similar to its namesake, the Factor OSTRO VAM. But they have little more in common than the design.
While we’re on the topic of the design and design language of the 2023 Factor OSTRO Gravel, we think it’s got some room for improvement. The stencil look and splatter paint job looks like something from 2010 (but it all makes a comeback eventually, right?). At least you can hide the somewhat unimaginative slogan “Never. Status. Quo.” with a top tube bag. There’s no hiding the fact that the 2023 factor OSTRO Gravel wants to look fast, and there’s no denying that it does, but it also looks a little crowded. The beefy fork and oversized bottom bracket area just don’t fit the overall picture, for example. Clearly, form follows function.
Factor Ostro Gravel
Seatpost Factor Seatpost
Brakes SRAM Red eTap AXS HRD 160 mm
Drivetrain SRAM Red eTap AXS 1x12
Stem Black Inc Aero Integrated Barstem 90 mm
Handlebar Black Inc Aero Integrated Barstem 430 mm
Wheelset Black Inc Thirty Four
Tires Schwalbe G-One R / Schwalbe G-One RS 700 x 40c
Size 49 52 54 56 58 61
Weight 8 kg
Black Inc components
generous tire clearance
mounting points on the top tube
The one-piece cockpit, which is available in different widths and lengths, and the wheels with 34 mm deep rims are supplied by Israeli brand Black Inc, which adds a touch of exclusivity and seems like a good match. The 2023 Factor OSTRO Gravel on test came equipped with different tires at the front and back, as is typical for MTBs, consisting of a Schwalbe G-One R up front, and a Schwalbe G-One RS on the rear, both of them 40 mm wide. This ensures low rolling resistance at the rear and more grip at the front. You should be able to fit up to 45 mm tires into the frame. The drivetrain is taken care of by a proven SRAM RED AXS 1x setup. To minimise friction and further improve efficiency, you get a CeramicSpeed bottom bracket. That’s a lot of high-end componentry for € 9,799. However, the one thing that gets in the way of you enjoying the thrill of speed is the integrated seat post clamp. It tends to gather dirt rather quickly and started squeaking during our tests, which is distracting and robs you of confidence.
Fun vs speed – Can the 2023 Factor OSTRO Gravel do both?
Judging by its looks, aero features, and Factor’s maxim (“Speed is your goal”), you naturally expect this gravel bike to be fast. And in fact, the 2023 Factor OSTRO Gravel feels fast. It makes pedalling hard fun as you can feel each rotation of the cranks being converted into propulsion. Especially when you’re already up to speed. It feels less sprightly than the Ridley Kanzo Fast or BMC Kaius 01 One when pulling away, needing a little more encouragement. At 8.0 kg, it isn’t nearly the lightest gravel race bike in the test field, but it still climbs admirably and won’t hold you back on long climbs or short ramps. The handling is responsive but not nervous.
For all those who like it hard and fast
That said, it takes a little practice to get used to the understeering. Initiating a turn needs some extra body English and happens more by shifting your weight than turning the handlebar, otherwise you’re likely to head straight for the next bush. Whether you can get used to the lack of comfort, on the other hand, is another question. All testers agreed: The 2023 Factor OSTRO Gravel and the BMC Kaius 01 share the title for the harshest ride. If you’re going to tackle long distances with this bike, then we hope you’ve got the physical conditioning to deal with every bump in the road. They will be passed on to you unmitigated. That said, the cockpit scores highly in terms of ergonomics. It’s only if you’ve got large hands that the drops could be too compact.
Factor OSTRO Gravel
|Seat tube||450 mm||468 mm||483 mm||500 mm||523 mm||545 mm|
|Top tube||520 mm||538 mm||553 mm||574 mm||591 mm||607 mm|
|BB Drop||76 mm||76 mm||74 mm||74 mm||74 mm||74 mm|
|Reach||377 mm||385 mm||394 mm||402 mm||412 mm||422 mm|
|Stack||515 mm||535 mm||555 mm||580 mm||605 mm||625 mm|
Who is Factor OSTRO Gravel for?
Anyone who really wants to have a go at getting on the podium at a gravel race will find a fast and aerodynamic partner in the 2023 Factor OSTRO Gravel. However, due to the lack of compliance and the slight understeer, the gravel race bike requires an experienced and fit rider. It might do well at big US-style gravel events covering 200 miles or less, but not much further than that, unfortunately. It’s the kind of gravel bike that fares better on long, straight stretches of hard-packed gravel than on playful singletrack.
Tuning tips: chainstay protector | more comfortable saddle from Specialized, Bianchi, or SQlab, for example | hide decals/give it a new paint job
Conclusion on the Factor OSTRO Gravel
The 2023 Factor OSTRO Gravel doesn’t just look fast, hard, and uncompromising, but also feels like that when you ride it! It’s a gravel bike for race day, designed with winning in mind through and through. It can definitely make you the leader of the pack, but the 2023 Factor OSTRO Gravel isn’t suitable for much more beyond that. However, that’s alright, because at least the focus on aero optimisation and speed is consistent with the overall concept.
- absolutely uncompromising race bike
- CeramicSpeed bottom bracket
- feels fast
- lack of comfort – harshest bike on test
- creaking seat post clamp that comes loose
You can find out more about at factor.com
For an overview of the test fleet head to the group test: Which is the best gravel race bike of 2023? 9 gravel race bikes in review
All bikes in test: Argon 18 Dark Matter | Berria Belador Allroad 8 | BMC Kaius 01 ONE | Canyon Grail CF SLX 9 eTap | Factor OSTRO Gravel | Fara Cycling F/All-Road | Ridley Kanzo Fast | Specialized S-Works Crux | Trek Checkpoint SLR 9 eTap
No, it’s not about perfect race tracks, it’s about efficiency. Fast, fleet-footed and efficient – those who want to speed along high-speed passages need a defined and spritely bike that accelerates with ease and efficiency. Nevertheless, reliable components are important too. We interpret “Smooth tarmac” bikes as follows: Hard efforts at high speeds with a maximum efficient bike on a consistently well-paved road. Effort-joy ratio: 80:30 (not everything has to be 100%!)↩
… also known as bike riding. Broken-up roads in the hinterland, deadlocked gravel roads, loose surfaces – sometimes muddy, sometimes bone-dry. For this, it takes bikes with super all-round, handling and wearing qualities uphill and downhill. Effort-joy ratio: 50:50↩
If you want to use your bike almost every day, you usually do not need an extremely tuned racing machine. Solid components, which are able to cope with the rigours of continuous usage in any kind of weather, are part of the basic equipment. At the same time, the bike should have practicable details: integrated fenders/assembly options, luggage racks/attachment points and a light system or at least the option of installing bike lights. The position on the bike should be rather relaxed, the overall comfort high, so that the Afterwork Ride becomes a cure and not a curse. Effort-joy ratio: 30:70↩
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Words: Martin Staffa Photos: Robin Schmitt, Jan Richter