Integrated aerodynamics. Total control. Unrivaled efficiency.  With the Propel Disc range, we set out to redefine speed. To achieve what was once unachievable. The frame is engineered with all-new airfoil shapes that are proven faster at various wind angles. It has the highest stiffness-to-weight ratio of any bike in its class. And it’s integrated with disc brake technology. This is how we define speed. Ultimate speed.


The Goal: Ultimate Speed.

The goal was clear: Forget limitations, ignore conventional wisdom, and create a race-winning aero road bike without compromises. To achieve what was previously unachievable.

Superior aerodynamics is a critical part of the equation, but our team of engineers, aerodynamics experts and pro racers wanted more. So we began the process of building an aero road machine that also delivers measurable gains in control and efficiency. It would have disc brakes integrated into the overall design. It would be light and stiff, and would offer previously unattainable aerodynamic performance. It's easy to improve aerodynamic performance by sacrificing stiffness or weight. But we committed to key design elements including a larger headtube, downtube and bottom bracket area that we feel are critical to the bike's efficiency and handling. These decisions help give the Propel Disc an even better stiffness-to-weight ratio and put it well ahead of competitors.

It took three years, radical experimentation with tube shapes, and hundreds of iterations in CFD and wind-tunnel testing, but the final results speak for themselves. The new Propel Disc range delivers ultimate speed with three key benefits: integrated aerodynamics, total control and unrivaled efficiency.

Integrated Aerodynamics

Using our AeroSystem Shaping Technology process, we took a holistic view of the bike as a complete system, analyzing countless combinations of frameset designs through CFD and wind-tunnel analysis. One of the key breakthroughs is a new truncated ellipse airfoil shape that delivers the best overall aero performance at various wind angles.

We also found that, with proper integration, a disc-brake design can actually improve aerodynamic performance. The final step was to refine the entire system at Aero Concept Engineering in Magny-Cours, France. We created a new integrated Contact SLR/SL Aero handlebar/stem unit with internal cable routing and an integrated Giant SLR WheelSystem with aero spokes.

The rear wheel has a taller 65mm rim depth, proven in wind-tunnel testing to produce minimal drag. The front wheel, which is more affected by crosswinds, features a shallower 42mm rim. This further boosts the bike’s aerodynamic performance by lessening the effect of crosswinds on the front wheel while also reducing overall drag. To accurately simulate real-world riding conditions, our team of aerodynamics experts created a dynamic mannequin. Other bike manufacturers use static mannequins, but only a dynamic one can accurately replicate the effects of a rider pedaling with various wind angles.

Total Control

With its new integrated disc-brake technology, the Propel Disc range delivers superior braking power and greater modulation in wet or dry conditions. This was a critical performance demand from our pro road racers, who typically race for hours on twisting terrain with high-speed descents and cornering before they make the decisive breakaway or sprint for the finish.

The integrated Giant WheelSystem further improves control. The rear wheel, less affected by crosswinds, has a 65mm deep rim for uncompromising aero performance and power transmission. The front has a shallower 42mm rim for added control in crosswinds. The result is a bike that not only accelerates and slices through wind faster, but also corners with greater precision and handles better in all types of racing situations.

Unrivaled Efficiency

The frameset of the new Propel Advanced SL Disc, including the new integrated stem and handlebar, is lighter than that of key competitor bikes including the Specialized Venge Disc and Trek Madone. Tests show that the Propel Advanced SL Disc frame is also stiffer than those competitor bikes.

A lighter chassis gives the new Propel Disc range a livelier ride quality, producing more explosive acceleration. Increased frame stiffness means better power transmission, enabling the rider to reach and maintain higher speeds with less effort. The combination of lower weight and higher stiffness adds up to unrivaled efficiency.