Giant launches “fastest ever” Propel aero road bike range

Giant has officially launched its all-new Propel aero road bike range, including the Propel Advanced SL that was ridden by Team BikeExchange-Jayco to two stage victories in the Tour de France, and the new model is said to be significantly more aerodynamically efficient than previously while also being both lighter and stiffer.

As well as the top-level Giant Propel Advanced SL, the line-up includes the less expensive Giant Propel Advanced Pro and the Giant Propel Advanced.

We’ve not ridden the Giant Propel Advanced SL yet, but we did have one to check out at the road.cc office last week.

Here are the headline claims – including a lot of stats – comparing the new Giant Propel Advanced SL with the previous generation:

• The new frameset is 225.5g lighter than before
• The frameset is 9.2% stiffer than before
• The back end of the frame is 85% more compliant than the previous generation
• The new model improves aerodynamic drag by 6.21 watts at 40km/h (25mph)
• Stiffness-to-weight ratio increases by 26.4%
• You can run tyres up to 30mm wide

Lighter, stiffer, lower drag, more comfortable… that’s the full house of claims that manufacturers tend to make for new bikes. Let’s see how Giant justifies those assertions.

Aerodynamic improvements

The Propel has always been the aero road bike in Giant’s range, sitting alongside the lightweight TCR which is more about stiffness to weight, so let’s kick off by looking at drag.

Take a look at our aero road bike reviews

“The guiding design principle behind the new Propel is its AeroSystem Shaping Technology,” says Giant. “It’s about analysing every tube, junction, angle and component — both individually and, more critically, as a holistic system.”

Giant has been using this AeroSystem Shaping Technology name for its approach for years. Like other brands, it starts off the design process using CFD (computational fluid dynamics) software before creating physical forms and moving on to the wind tunnel.

“AeroSystem Shaping is what led engineers to use the signature truncated ellipse airfoil shapes that can be found in key areas of the frameset including the down tube, seat tube and seatstays. Working with renowned aerodynamicists at the GST wind tunnel in Immenstaad, Germany to accurately simulate real-world riding conditions, they use a dynamic mannequin [with moving legs pedalling at a cadence of 90 rpm] to analyse the aerodynamic factors of not just the bike, but rider and bike together.”

Check out our review of the Giant TCR Advanced SL 0 Disc

Most manufacturers either measure the bike in isolation or with a static mannequin on board. Giant’s testing is repeated at various speeds and at yaw angles (the angle the bike is positioned relative to the flow of air in the wind tunnel) of -20° to +20°.

“The frontal sections, where aerodynamics matter most, feature sculpted lines and that truncated ellipse shape to minimise drag,” says Giant. “We even created two different water bottle cages (one for the down tube, one for the seat tube) to minimise aerodynamic drag for each of these specific tubes.”

Although they look similar, the width of the base of the bottle cages matches their respective tubes.

“When comparing the complete new Propel Advanced SL bike to the previous generation, the new model improves aerodynamic drag by 6.21 watts; a 2.6% aerodynamic improvement,” says Giant. “This equates to a saving of 27 seconds over 40km at 40km/h.”

We need to do our usual explanation of that type of statistic here. Of course, anything moving at 40km/h will cover 40km in the same amount of time: an hour. What Giant means is that you’ll be able to achieve that speed at a slightly reduced power. If you rode at the same power, you’d cover 40km in 59:33mins.

It’s important to note that the claim relates to the bike as a whole and that the new proprietary Contact SLR Aero handlebar and stem, and the new Cadex 50 wheels and Cadex Aero tyres are said to contribute to the reduction in drag.

Cadex reveal new 50 Ultra Disc wheelset and Aero tubeless tyres “engineered for outright speed” 

Giant’s statistics compare the new model built up with a Cadex 50 Ultra WheelSystem and 25mm Cadex Aero Race tyres, versus the previous generation with a deeper section Cadex 65 rear wheel and a shallower Cadex 42 front wheel with 25mm CADEX Race tyres.

Giant hasn’t released aero figures that compare the two bikes fitted with the same wheels, or the framesets in isolation.

Increased stiffness-to-weight ratio

Giant says that the new Propel Advanced SL uses its “most premium raw carbon fibre and cutting-edge manufacturing techniques to achieve a greater stiffness-to-weight ratio than the previous generation.”

We’ll come back to weight in a mo and focus on stiffness here.

“When determining the precise tubing shapes and diameters, along with the layup of the Advanced SL Composite material that’s used to create the frame and fork, [our] engineers focused on two key areas of stiffness: frame stiffness, which determines the amount of overall frame and fork torsional flex under load, and pedalling stiffness, which measures the lateral flex of the bottom bracket area under load,” says Giant.

It says that its engineers have modified sections of the head tube, down tube and bottom bracket area to produce most of the gains in stiffness.

“Testing reveals that the new frame has 9.9 percent greater frame stiffness than the previous generation. Pedalling stiffness gets a 7.5 percent boost. The overall stiffness of the frameset, including the frame and fork, is 9.2 percent higher.

“When you combine those figures with the overall weight of the frameset, you get the magic number that reveals overall efficiency, or stiffness-to-weight. In the case of the new Propel Advanced SL, the reduced weight and increased stiffness work out to a gain of 26.4 percent in overall efficiency.”

More compliance

Giant points out that simply stiffening a frameset doesn’t always make it faster. Factors like compliance and control also come into play in determining the overall performance.

With this in mind, the seat tube, chainstays and integrated seatpost have all been re-engineered with the aim of smoothing the ride. They’re noticeably slimmer than on the previous generation Propel Advanced SL.

“This new design helps reduce weight, and it also gives the new Propel improved road handling,” says Giant. “Compared to the outgoing Propel Advanced SL, the new model has 85% added rear-end compliance (via the new integrated seatpost), making it more capable for long, hard days in the saddle, when its road-smoothing properties help minimise fatigue.

“Added frame and fork clearance also allow you to run larger diameter tyres (up to 30mm) for an even smoother ride.”

Easier adjustment

The Giant Propel Advanced SL’s cockpit has been redesigned with a new two-piece Contact SLR Aero handlebar and stem setup that’s intended to make it easier to change components and adjust your fit.

“This new OverDrive Aero system keeps the cables and hoses hidden from the wind while avoiding the complexities associated with fully integrated handlebar/stem designs that are common with many of today’s aero road bikes,” says Giant.

“The new Contact SLR Aero carbon handlebar has flattened tops for aero efficiency and hand comfort, along with a deeper drop for added control while sprinting, cornering and descending.”

Giant’s previous Contact SLR Aero cockpit routed cables above the stem and into the frame behind the steerer tube, hidden out of sight – and away from the wind – by a cover.

With the new design, brake hoses and cables (if there are any) are routed through the bar, and before emerging in the centre and travelling underneath the new channelled Contact SLR Aero stem and into the frame in front of the D-shaped steerer. Although the hoses/cables aren’t visible unless you view from below, they don’t run inside the stem and any headset spacers you use are of a two-part interlocking type.

Cables for mechanical shifting follow the same routing.

All of this means you can adjust the front end height and swap the stem easily. It also gives the bike a clean look.

Weight

The new Giant Propel Advanced SL frameset (size medium, including hardware) has a claimed weight of 1,429.5g

This is 225.5g lighter than the published weight for the previous model (1,655g), a saving of 13.6%.

The new Contact SLR Aero cockpit is said to reduce the overall weight of the new Giant Propel Advanced SL by a further 102.5g.

The previous handlebar, stem and stem cover were a combined 462.5g while the new setup is a claimed 360g. That’s a 22% saving.

The finish you see here is called Carbon Smoke, which is a clear coat lacquer with a small amount of paint in it, the idea being to keep the weight as low as possible. All colouring is applied as decals.

The complete Giant Propel Advanced SL (ML size, Shimano Dura-Ace Di2 build) that came to road.cc HQ last week hit our scales at 6.96kg. Giant says it was 6.8kg on their scales.

Giant Propel Advanced Pro

The Giant Propel Advanced Pro uses the same truncated ellipse airfoil tube profiles as the Giant Propel Advanced SL and the cables route underneath the stem and into the frame in front of the D-shaped fork steerer in the same way.

Whereas the Propel Advanced SL is made from what Giant calls its Advanced SL-Grade Composite, the Advanced Pro uses its Advanced composite. It doesn’t benefit from all of the Propel Advanced SL’s manufacturing techniques, such as the laser cutting of swatches of composite that then go through an automated assembly process to place them precisely in key areas of the frame and fork to keep weight down.

The other big difference is that whereas the Giant Propel Advanced SL has an integrated seatpost (ISP), the Propel Advanced Pro has a removable Vector seatpost. Putting that ISP to one side, the geometries are identical.

Like the Giant Propel Advanced SL, the Propel Advanced Pro gets a full-carbon fork, aero bottle cages, and 50mm deep rims.

Giant hasn’t published a frameset weight for the Propel Advanced Pro.

Giant Propel Advanced

The Giant Propel Advanced’s frame is the same as the Propel Advanced Pro’s – so the tube profiles and cable routing system are the same across the whole Propel range – although the fork comes with an alloy steerer rather than being full-carbon.

Giant hasn’t published a weight for the frameset.

Specs are lower, making the Giant Propel Advanced the most affordable option in the lineup – although prices are yet to be released

One bike to rule them all?

Over the past few years, we’ve seen aero bikes becoming lighter and lightweight bikes taking on aero features and Specialized has even retired its aero Venge and called the Tarmac SL7 ‘one bike to rule them all’.

Some people have looked at pictures of the new Propel in the Tour de France and speculated that Giant intends this model to take on a similar role. Giant insists this is not the case.

Read our review of the Giant TCR Advanced Pro 1 Disc

Granted, Giant claims that the new Propel is lighter, stiffer and more compliant than previously, muscling in on the TCR’s territory to some extent, but it points out that the TCR is lighter still. Giant gives a frameset weight (painted frame, painted uncut fork, integrated seatpost, seat clamp, front and rear derailleur hangers) of 1,265g for the TCR Advanced SL Disc, compared with 1,429.5g for the Propel Advanced SL. 

One bike to rule them all: why lightweight aero bikes are now THE essential Tour de France race weapon

You can run 32mm tyres from most brands on the disc brake bikes in Giant’s TCR range whereas the Propel takes a maximum width of 30mm.

Giant has no intention of sidelining the TCR and making the Propel its one flagship road model.

Models, prices and availability

Each frameset is available in various builds:

Giant Propel Advanced SL 0 (above)
Groupset Shimano Dura-Ace Di2 (inc power meter)
Wheels Cadex 50 Ultra Disc WheelSystem

Giant Propel Advanced SL 1
Groupset SRAM Force eTap AXS (inc Giant Power Halo power meter)
Wheels Cadex 50 Ultra Disc WheelSystem

Giant Propel Advanced Pro 0 AXS
Groupset SRAM Force eTap AXS (inc Giant Power Halo power meter)
Wheels Giant SLR 1 50 Carbon Disc WheelSystem

Giant Propel Advanced Pro 0 Di2 
Groupset Shimano Ultegra Di2 
Wheels Giant SLR 1 50 Carbon Disc WheelSystem

Giant Propel Advanced Pro 1
Groupset SRAM Rival eTap AXS (inc Giant Power Halo power meter)
Wheels Giant SLR 1 50 Carbon Disc    

Giant Propel Advanced 1 
Groupset SRAM Rival eTap AXS
Wheels Giant SLR 2 50 Carbon Disc

Giant Propel Advanced 2
Groupset Shimano 105
Wheels Giant P-A2 Disc                             

Giant has decided not to offer a Propel in a Shimano 105 Di2 build. This is because the highest gearing Shimano is providing in this groupset for the 2023 model year is a 50/34-tooth chainset with an 11-34-tooth cassette.

Giant decided that this gearing doesn’t suit the Propel so specced Rival AXS instead. 

There are no Propel frameset options for this model year because Giant felt that component supply for custom builds would be hit and miss.

Giant expects the new Propels to be delivered to the UK in November. With the world economy being unsettled right now, it has decided not to publish UK pricing until just before their arrival. 

The only pricing that has so far been released is for Australia. For what it’s worth, those prices are:

• Propel Advanced SL 0, $13,999 AUD (around £8,150)
• Propel Advanced Pro 0 AXS, $8,499 AUD (around £4,950)
• Propel Advanced Pro 0 Di2, $7,799 AUD (around £4,540)

However, there’s no guarantee that the UK prices will be exact equivalents.

www.giant-bicycles.com