The Propel Disc range also introduces new purpose-built Giant components including an aero handlebar-and-stem unit with internal cable routing, and aero WheelSystems optimized with different rim depths front and rear to reduce drag without sacrificing control or power transmission.
The goal with the new Propel Disc range was to create a race-winning aero road bike with zero compromises in weight, stiffness and overall race handling. Superior aerodynamic performance was a critical factor, but Giant pro racers including Tour de France stage winner Michael Matthews—who tested and raced pre-production versions of the bike earlier this year—demanded that it also deliver measurable gains in efficiency and control.
It took three years, radical experimentation with tube shapes, hundreds of iterations in Computational Fluid Dynamics, and innovative wind-tunnel testing with a dynamic mannequin, but the final results speak for themselves. The flagship model of the range, the Propel Advanced SL Disc, has the highest stiffness-to-weight ratio of any bike in its class, and wind-tunnel tests reveal a lower drag coefficient at a wider range of yaw angles than its non-disc-brake predecessor.
Matthews raced on pre-production versions of the Propel Advanced SL Disc earlier this year, including at the Tour de France. Following a rainy Stage 2 at the Tour, he said: “With all the new aerodynamics, this bike is super fast. When you need to accelerate, it really gives you that kick that you need. And even in the rain, with the disc brakes it’s perfect.”
The core concept behind the new Propel Disc range is Giant’s AeroSystem Shaping Technology. Viewing the bike as a complete system, rather than an assembly of a frame and components, engineers analyzed countless combinations of airfoils, tube junctions, wheels and components through CFD and wind-tunnel testing.
One of the key breakthroughs is a new truncated ellipse airfoil shape—a design that lowers drag at a wider range of wind angles than traditional “teardrop” frame tubing. Engineers also found that, with proper integration, a disc-brake design can actually improve aero performance compared to rim-brake configurations.
With its new integrated disc brakes, the Propel Disc range delivers superior braking power and greater modulation in wet or dry conditions. This was a critical performance demand from Giant pro racers. The frame is engineered with flat disc-brake mounts, along with front and rear thru-axle configurations for added stiffness and steering precision. Aerodynamic testing also reveals that the bike’s disc-brake integration reduces overall drag compared to traditional rim brakes. Oncoming air flows smoothly through a more open fork crown area, and the asymmetric fork design helps push air around the front disc-brake caliper more efficiently.
Another big demand from Team Sunweb pros was efficiency, as measured by stiffness-to-weight ratio. The flagship Propel Advanced SL Disc model frameset is lighter than that of key competitor bikes including the Specialized Venge Disc and Trek Madone. And tests show that it is also significantly stiffer than those competitors. The combination of lower weight and higher stiffness means that the new Propel Advanced SL Disc is more efficient on the road.
Beyond the chassis, the Propel Disc range features several new component innovations including an integrated Giant WheelSystem. The rear wheel, less affected by crosswinds, has a 65mm deep rear rim for uncompromising aero performance and power transmission. The front has a shallower 42mm rim for added control in crosswinds. This further boosts the bike’s aerodynamic performance by lessening the effect of crosswinds on the front wheel while also reducing overall drag.
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.
Up front, the new Contact SLR/SL Aero handlebar/stem unit was designed with internal cable routing to optimize aerodynamics. And while overall aero performance was always at the forefront of every design decision with the new Propel Disc range, the engineering team was mindful to never compromise weight or stiffness. It’s easy to attain better aero numbers by sacrificing stiffness or weight, but engineers committed to key elements including a larger headtube, downtube and bottom bracket area that were deemed critical to the bike’s efficiency and handling.
Here’s a look at the three series in the all-new Propel Disc range:
Propel Advanced SL Disc: The flagship model of the new Propel Disc range is engineered with Giant’s highest-grade Advanced SL composite material. Already tested and proven at the highest levels of professional racing by Team Sunweb sprinting specialists, it has the highest stiffness-to-weight ratio of any bike in its class. Every model in this series includes the Contact SLR Aero handlebar-and-stem unit with a wind-tunnel shaped airfoil design and internal cable routing for optimal aerodynamics. It also features new Giant SLR Aero WheelSystem with a 65mm rear rim depth and 42mm front rim for the perfect balance of aero speed and control in crosswinds. As part of a complete Tubeless System, these wheels are matched with Giant’s new Gavia tires.
Propel Advanced Pro Disc: Extensive CFD analysis and dynamic wind-tunnel testing were used to optimize every frame tube and angle in a process called AeroSystem Shaping technology. The frame is handcrafted using Advanced-grade composite material to produce a bike that’s lightweight and stiff, with a sharp, responsive ride quality. Disc brakes are integrated with the frame using flat-mount calipers, thru-axles and an asymmetric fork to maximize aerodynamic performance. This series features the Giant SLR 1 Aero WheelSystem with a 65mm rear rim depth and 42mm front rim for the perfect balance of aero speed and control in crosswinds. These Tubeless Ready wheels are integrated with Giant’s new Gavia tires to deliver seamless Tubeless System performance. This series also includes the Contact SLR/SL Aero bar and stem designed to reduce overall drag.
Propel Advanced Disc: Engineered with AeroSystem Shaping technology and Advanced-grade composite, this series delivers proven aero performance and one of the lightest frames in its category. New integrated disc brake technology includes flat-mount calipers and thru-axles for wheel stiffness and streamlined performance. This series features the Giant SLR 1 Aero WheelSystem with a 65mm rear rim depth and 42mm front rim for the perfect balance of aero speed and control in crosswinds. As part of Giant’s Tubeless System, the wheels are integrated with new Gavia tubeless tires for added rolling efficiency and a reduced risk of flats.