3 years ago Giant began redesigning their successful Propel Aero road bike frame that has seen multiple successes under the likes of Marcel Kittel.
Convinced that the UCI would have ratified the use of disc brakes by the time they released the bike, they committed 100% to creating the new frames in a disc-only option.
While this may seem like an oversight, it is pretty safe to assume that the technology is here to stay and since the pros are already racing on discs and more and more so, it is likely to be ‘UCI legal sooner rather than later. There are some acute benefits to be had from a ground-up approach that builds aerodynamics around a disc brake, rather than retro-fitting discs onto already existing frame and fork designs.
The development of a frame that builds its aero footprint with the disc in mind will be advantageous since the discs can be factored into the airflow, and the areas they occupy on the bike optimised to minimise disruption through novel fork and frame construction at those points.
Giant’s new Propel Disc frame and cockpit has a total weight that is lighter than the competition. Giant quotes a 414g saving over the Specialized Venge VIAS Disc and a 229g saving over the Trek Madone. More importantly, the Propel Disc also has greater drop-out to drop-out stiffness than the competition and boasts a 35% improvement in stiffness over its own rim brake Propel SL. Indeed, the Propel Disc has the highest stiffness to weight ratio of any bike in its class.
Beyond the weight and stiffness – and the bigger issue when comparing aero road bikes - is the aerodynamics. Giant spent a lot of time in the wind-tunnel at the Magny Cours test circuit with their competitors’ bikes. In all of their testing the Propel Disc out performed all of its main competitors. This is particularly important when you take into account that Giant are the only company to test at multiple yaw angles with a moving cycling mannequin. Other companies test using static dummies but none go as far as to investigate airflow in ‘normalised’ cycling conditions. As such not only are their results impressive, they are also the most reliable when making statements about aerodynamic efficiency in real-world conditions. Giant are currently trying to get their results independently verified.
The new aero benefits stem in part from the integration of the disc brakes into the overall design. Specifically designed frame and fork mounts are designed exclusively for flat mount disc calipers which position the calliper closer to the frame and fork and allow for smaller 140mm rotors. The Propel Disc features 12mm bolt-thru axles front and rear for better brake modulation and stiffer front and rear end.
In addition to the integrated disc brake design, Giant have re-engineered the cockpit. Previous models have used a completely integrated one-piece bar and stem. The new Propel Disc features a brand new cockpit with airfoil design honed in the wind-tunnel. This new Contact SLR Aero bar and stem not only improves aerodynamics but simplifies bar-stem choice for the application of bike fit whilst simultaneously simplifying the process of swapping out the bar or stem should a change be necessary from a bike fit perspective. This is achieved by having the cables internally routed but accessible through a top-plate that covers the cables and enhances the aerodynamics.
Like all Propels, the new Propel Disc uses Giant’s AeroSystem Shaping Technology. Using CFD (Computational Fluid Dynamics) and wind-tunnel data, Giant’s engineers have optimised each tube shape to deliver superior aerodynamic performance. The integrated seatpost (ISP) of the SL also plays an integral part in improving aerodynamics through tube shape whilst also adding improved compliance and saving 45g over a non-ISP variant.
Developed primarily to give all the possible aero advantage for a road bike, the Propel Disc platforms deliver on stiffness, weight and comfort making it an accomplished and versatile bike for the rider looking to maximise on a single purchase. Ideal for long-course or technical Triathlon where aero counts as much as comfort; in a race where you feel you have the legs for a solo flyer or for beasting your clubmates in the lampost sprints!
Giant only uses the finest quality Japanese Torayca carbon fibre in all their frames: the ‘Advanced’ a T700 (found in both the Advanced and Advanced PRO framesets) and the ‘Advanced SL’ a T800 fibre used in the Advanced SL. The difference is found in the rate at which the fibre is produced. A lengthier process produces a stronger fibre which means that less can be used for the same stiffness and strength. The production cost increases dramatically as the quality increases, which is reflected in the price you pay for the final product. For the Propel Disc, Giant have also employed Continuous Fibre technology. This method of frame construction utilises longer runs of carbon fibre allowing for greater strength and less material to yield significantly lower frame weights without compromising on strength and stiffness. Thus, the Propel Disc has Giant's highest stiffness to weight number and the low weights are impressive when considering the additional material used to form the aero profiles and especially remarkable when compared to frames of just 5 years ago.
The Giant Propel Disc frameset is aerodynamic, remarkably light, astoundingly stiff under load, smooth and incredibly precise in the corners yet comfortable enough for hours in the saddle. It is a phenomenal platform that bests the competition without commanding the price tag of other manufacturers' equivalents. The integration of disc brakes improves both the stopping power in all conditions as well as the aerodynamics – no small feat.
The Giant Propel Advanced SL0 features a full Shimano Dura Ace 9100 series electronic Di2 11 speed groupset which includes Shimano's new Dual-sided crank based Power meter for accurate metrics.These are partnered with hydraulic disc brakes and Shimano's Ice-tech rotors for improved cooling while braking. Wheels are Giant's own superb lightweight, full carbon SLR 0 Aero Disc with front and rear 12mm Thru Axles for improved stiffness and more reliable braking. The variable wheel depths (65mm rear and 42mm front) deftly balance speed with handling for a fast but predictable ride. The Wheels are tubeless and are supplied with valves and sealant. In addition, Giant supply their RideSense frame mounted speed and cadence sensors for use with a host of cycling computers, Smart Trainers and GPS units.