The iconic bike whose unbeatable aerodynamics and speed changed gravel riding forever, now in a modern evolution.

A special livery to celebrate 10 years of exploro on our gateway to gravel.

It All Starts with the Tires

To design a fast bike, you have to start with the wheels. Tire choice determines comfort and grip, but also affects aerodynamics and even frame design. And to design around aerodynamics, you need to know the real tire dimensions; the ones you actually measure. That’s what REALFAST aerodynamics means: reality, not theory.

Tire size and shape depend on rim width, tire pressure, and even the accuracy of the manufacturer’s stated dimensions.

So we ran hundreds of tests and measurements to map the actual tire dimensions, what we call WAM (Width As Measured) and RAM (Radius As Measured), and used those numbers to design the frame.

Realfast Aerodynamics

Aerodynamics matter even off-road.

You notice it most when you’re not grinding uphill, but riding on tarmac or smoother gravel. With headwinds or crosswinds, even if your ground speed is moderate, you’re still moving fast relative to the air; and that’s exactly why aerodynamics make a difference.

PRIMO² is also a great road bike in its own right. That’s because we designed, tested, and optimized it not only at 30 mph (48 km/h) the wind tunnel standard for road bikes, but also at a more realistic 20 mph (32 km/h), which better reflects off-road gravel, dirt, and singletrack speeds.

Sqaero

PRIMO²’s aerodynamic performance starts with its down tube. At 50×75 mm with a truncated Sqaero profile, it provides not only optimal stiffness, but also the ideal shape to guide airflow around a wide front tire.

Designing a full airfoil starting from a 50 mm width (needed to continue the airflow from the front wheel) would require a profile height of 150–200 mm creating too much surface drag. With the truncated Sqaero profile, even the bottles remain shielded from airflow.

To optimize REALFAST aerodynamics across the entire platform, we applied the Sqaero profile not only to the down tube, but also to the head tube, fork, seatpost, and seat stays.

Primo² versus Racemax, Extrema and Ultra

Racemax and Extrema Italia all feature gravel-specific geometries. Racemax is designed as the ultimate choice for fast gravel or racing; when speeds get serious.

Extrema Italia excels in non-stop ultra adventures and the toughest off-road races, while Ultra combines exceptional ground clearance for extreme terrain with efficient aerodynamics.

Primo², by contrast, has a road-inspired geometry while still offering wide tire and wheel options. Ride fast on 700c wheels, then switch to 650b and bigger tires when adventure calls.

Sqaero Fork Legs

Sqaero fork airfoil, perfect to guide the airflow around the front wheel and boost fork stiffness.

Sqareo Headtube, Downtube and Seattube

Sqareo frame shape complete the aero fork blades

Drop Chainstay on Drive Side

Dropping the drive-side chainstay improves tire & crank clearance.

Tire Clearance

Fits up to 700 x 45mm tires and even 27.5”x51mm (2.0”), while keeping 4mm between any frame part and tire.

1x and 2x Compatibility

1x for simplicity and efficiency - 2x compatible

3t Semi-Integrated Technology

The perfect design solution for clean cable integration. Compatible also with 1x and 2x mechanical groupsets.

Threaded BB

All the Primo complete bikes come with threaded BBs without any alloy rings in the carbon (avoiding added weight, complexity and debonding risk).