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Ostro Gravel

Aero gravel race bike

Discover the all-road all-star

Speed is your goal. Every ride, whatever the surface, faster is what counts, and this is the gravel bike you’ve been waiting for. The OSTRO Gravel takes its ‘win everywhere’ mentality from its road racer stablemate, the OSTRO VAM, and is likewise developed to dominate its category with incredible aero, superior handling, high stiffness and low weight. With a tire capacity of 45mm, it’s ready to go anywhere, fast.


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Real-World Gravel Aero

Gravel racing is fast and aero really matters, but it isn’t as fast as road racing so the requirements are different. The OSTRO Gravel frame is carefully optimized for the speeds at which you’ll be riding. Our team used a ‘zoned aero’ strategy which focused the front of the bike on aerodynamics because it meets clean, or freestream, air flow, and the rear of the bike on lightness, where the air flow is too chaotic and ride quality is the priority. In particular, a lot of time was spent on the head tube, where an all-new tube shape unlocked significant drag reductions by manipulating the ‘laminar separation bubble’ that occurs near the front of airfoils at lower speeds. The tech is rooted in aerospace but all you really need to know is that the OSTRO Gravel will get you to your finish line faster, and by minutes, not seconds.

45mm Tire Clearance

The OSTRO Gravel offers a generous 45mm of tire clearance in both 700c and 650b, giving you the options and possibilities to tackle the toughest routes and events. This is a real figure, with 4mm of clearance either side in accordance with ISO standards, so the OSTRO Gravel is super-capable in muddy conditions. That was proven at the queen of gravel races, the 2022 Unbound 200, where heavy rain made the course brutal and the OSTRO Gravel was ridden to a top-10 finish.

Black Inc THIRTY FOUR Carbon Gravel Wheels

The new Black Inc THIRTY FOUR wheels are - like the OSTRO Gravel itself - dedicated to speed on gravel. Their 34mm depth maximizes aero gains while keeping weight to a minimum and avoiding too tall a combined rim and tire side area, ensuring crosswind stability. They’re most aero with a 32mm tire for all-road use, yet also very effective for gravel tires up to 43mm. The internal width of 25mm allows bigger tires to take a better shape. The hookless rim is designed to make it easy to mount tubeless tires, in most cases with a regular floor pump. The rim includes a secondary shoulder which keeps the tire securely seated in the event of a rapid deflation, allowing you to come to a controlled stop. The Black Inc hubs run on CeramicSpeed bearings for ultimate efficiency.

Black Inc Integrated Aero Barstem

Aerodynamics and ergonomics - the flared Black Inc Integrated Aero Barstem takes both to new heights, because riding far and riding fast are not mutually exclusive. Its mid-depth aero profile is the outcome of tireless research and development, initially using CFD (computational fluid dynamics), then by testing prototypes in a wind tunnel. The result is that it outperforms leading brands of aero road bars and does so at an exceptionally low weight. What’s more, it’s as comfortable as it is fast, thanks to highly refined ergonomics which provide more back sweep for a natural wrist angle on the tops, more wrist clearance and hand positions thanks to the chamfered corners, a drop shape that accounts for the longer reach of the latest Shimano and SRAM shifters and a 7-degree flare that starts below the shifter mounting point. The flare adds 3cm of width in the drops, a figure carefully judged to suit all applications as the Integrated Aero Barstem is designed to pull double-duty for both the OSTRO Gravel and OSTRO VAM. For gravel, enjoy the extra control of the wider drops in descents; for road use, select your usual drop width and benefit from the much more aero position achievable on the narrower hoods. The new Integrated Aero Barstem also gains a GoPro-style computer mount, adding angle adjustment and a more supported second mount for a light or action camera.

Steering Geometry Optimized For All Tire Sizes

Many all-road and gravel bikes struggle to deliver steering that’s effective and confident both on- and off-road, typically ending up with an unsatisfying compromise of soft handling and modest tire capacity. The OSTRO Gravel breaks that mold by making the tire size an integral part of the geometry. Wider tires also have a greater outside diameter (or rolling circumference) which increases the true, or ‘resulting’ trail of a bike; narrower tires have a smaller outside diameter which reduces resulting trail. These outcomes match the handling response you want when riding those respective tires, so we designed with resulting trail as the priority. We selected a trail value on the slightly faster handling side for gravel use, given the bike’s racing focus, while prioritizing head tube angle when selecting our fork rake. This leads to a fast handling gravel bike on 43mm tires and an equally satisfying and precise all-road machine on 32s, with no low-speed wheel flop.

Look At The Scenery - It’s A Blur

When you’re riding full gas, there’s little time to appreciate anything about the countryside other than how fast it’s rushing by. The OSTRO Gravel was made for these rides, with an unrivalled combination of aero, lightness, compliance and integration. Put your head down and go.

Best-In-Class Weight

At only 900g, the OSTRO Gravel is one of the lightest gravel frames available. We have used the very best materials to reach such a low weight for an aero frame, ensuring that lightness is matched by sensational ride quality and the immense durability you want for season after season of epic gravel racing.

Carbon Compliance And Aero Performance

Leveraging our in-house carbon expertise, we have precisely shaped the OSTRO Gravel’s tubes to create a tuned ride with optimized performance characteristics. The head tube has received an entirely new shape compared to the road OSTRO VAM to enhance its aerodynamic properties at gravel speeds. The remainder of the frame uses the proven tube profiles from the OSTRO VAM, providing both snappy performance and aero efficiency.

Electronic Shifting And Disc Brakes Only

In line with rider demand and facilitating a reduction in aero drag and weight, the OSTRO Gravel is built exclusively for electronic shifting groupsets and disc brakes. Cable and hose routing is fully internal.

While the OSTRO Gravel pairs ideally with the Black Inc Integrated Aero Barstem, we have designed the front end to be easily compatible with various third party internal routing systems, so you can always have the exact touch points you want.

The T47 standard for threaded bottom brackets ensures a secure fit and easy maintenance. It allows for the use of a wide range of crank spindle diameters and helps keep the bottom bracket shell robust for exceptional power transfer.

To be self-sufficient in the world’s hardest gravel events, you need extra carrying capacity. We have added mounting bosses to the top tube and down tube so that you can make it feed stations or gas stations, even on the toughest days.

Our engineers chose a round steerer, proven to be the most durable solution serious gravel riding and racing. The 1-½” upper and lower bearings with a modified split ring allow for the cables to pass through the bearing, easing maintenance demands.

Basing our fork offset on the size of the frame ensures optimum handling characteristics across all frame sizes so that every customer has the best ride experience.

FrameTeXtreme®, Toray®, Nippon Graphite® Pitch-Based Fiber
ForkOSTRO Wide Stance Fork
Seatpost0 and 20mm setback available
BarstemBlack Inc Integrated Aero Barstem Reach 80mm, drop 120mm. Multiple stem lengths and bar widths available
HeadsetCeramicSpeed SLT 1.5″ bearings
Head Tube Diameter1.5″ upper and lower
Saddle Rail Clamps7x7 and 7x9
Bottom BracketCeramicSpeed T47A Aluminium cups / CeramicSpeed bearings available for DUB, 24mm, or Ultra-Torque
Cable RoutingInternal
Compatible ComponentsElectronic
Brake typeDisc
Max Rotor Size160mm front & rear
Max Chainring52-tooth
Front Axle12 x 100mm thru-axle
Rear Axle12 x 142mm thru-axle
WheelsetBlack Inc THIRTY FOUR
Wheel Size700c
Max Tire Clearance45mm measured
Manufacturer WarrantyLimited Lifetime Warranty
A Stack515535555580605625
B Reach377385394402412422
C Head Tube Angle71.2°71.3°72.2°72.3°72.3°72.3°
D BB drop767674747474
E Trail626261616161
F Fork Rake/Offset565650505050
G Chainstay Length420420420423425425
H Wheelbase99910131014102910471069
I Bike Standover Height750767786802820847
J Seat Tube Length450468483500523545
K Seat Tube Angle74.5°74°74°73.5°73.5°73.5°
*All dimensions in mm.
Left Quote

The OSTRO Gravel is the race bike of my dreams. It’s so fast - I’m telling you, you can really feel it. It’s also super-light and I love the handling. I’m so excited about taking it to all the races coming up.

Adam Roberge, 2022 Gravel World Champion

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