After holding off longer than many experts predicted, Giant has finally taken the plunge into the aero road bike market.
The Propel Advanced SL, which will go head-to-head against the Cervelo S5, Specialized S-Works Venge, Ridley Noah FAST and Scott Foil, took more than three years and 88 development and design reviews to complete the journey from concept to reality.Most notable at first glance is the very level top tube – Giant designers pioneered the sloping top tube and compact geometry, and that’s what you expect to see when you look at a Giant, but the Propel’s top tube is near horizontal. Key to the frame is the AeroSystem Shaping technology that is the result of Computational Fluid Dynamics (CFD) research and wind-tunnel tests. Every tube has been carefully shaped, with a teardrop shape in evidence wherever you look. Interestingly, it’s clear that the downtube has been formed with a water bottle in mind. It’s flattened to a degree roughly where the water bottle normally protrudes from the sides of a conventional down tube.
An intriguing side note to the CFD testing is that the results were the inspiration for the colour scheme on the SL Advanced.
“When we looked at the CFD results, the aero qualities of the bike were obvious,” Eric Klemm says. “The air around the front of the bike frame was relatively still and calm, as was the space around the top tube, downtube and bottom bracket. Toward the rear of the seatpost, however, was where the turbulence began, as the bike cut cleanly through the wind and then spat out all the churned-up air behind it. The image on the screen showed up dark and calm at the front of the bike, bright and volatile at the back – so we thought, why not model the paintwork around the CFD image?”
So what makes the Propel different to any other aero road bike?
According to Giant’s Global On-Road Manager Jon Swanson, “this bike doesn’t suffer from the usual tradeoffs associated with aero bikes. Generally you sacrifice weight in order to improve aerodynamics, or have to be willing to forego frame stiffness. When we developed this bike we simply weren’t prepared to compromise, and the end result is the lightest, most aero bike in this section of the market, and its frame is among the stiffest too.”
Component integration is key with aero road bikes – keeping the airflow smooth over the frame and fork forces a rethink with components like brake callipers. Giant’s SpeedControl SLR carbon composite mini-V brakes are located behind the fork and in the usual location on the seat stays. The entire system lines up beautifully with the rest of the frame, no doubt contributing to the impressive overall aero effect but also looking snug and neat. Unlike some other linear-pull brake systems I’ve come across, this is as close as you’ll get to a true quick-release: a quick squeeze of the brake arm between thumb and forefinger does the trick.
However, the brakes didn’t perform to the level that their appearance suggested, especially not at first. To be fair, the bike I test rode had never been ridden, not even across the shop floor, and the brakes had not had a chance to bed in, but the mushy feel with an occasional surge of extra power was a little off-putting. About 20km into the ride the rear brake began rubbing the wheel, but after adjusting one of the tension screws the pads came back into parallel and the problem disappeared – 50km in and the brakes became more predictable and consistent (or maybe I just got used to them, but either way they ceased to be an issue).
The integrated Control SL aero cockpit handlebar system not only looks neat and fast, but feels stiff, responsive and secure – it also does a reasonable job of damping road vibration. A couple of other features of the Control SL bar system that score points for neatness and innovation: the control module and power source for the 11-speed Shimano Dura-Ace Di2 9070 groupset is housed in a purpose-built PVC container under the head stem, where it stays dry, out of the way and is balanced centrally. Also, tiny ‘satellite shifters’ can be found on the inside of the bars in the drops – one flick with your thumb and you’ve upshifted without moving your hands or taking your eyes off the road. These can be moved easily if required, as they are held in place only by the bar tape. And – here comes the good bit – when the genuine aero bar extensions are clipped on, the cabling and satellite shifter for the rear derailleur can be routed through the centre. Presto, an instant TT/triathlon bike!
On the subject of triathlons and multisport racing, this bike is a great fit for that market. As aero as most other rides out there, with super stiffness and great cornering and climbing capabilities, it could well negate the need for triathletes to fork out big bucks for a road bike and a TT bike.
Pro triathlete Dr Mitch Anderson seemed pretty impressed with the diversity it offered, as was Olympic bronze medallist Erin Densham.
“This bike (the Envie) covers a lot of bases,” said Densham. “At the top level, particularly over the Olympic distance where we don’t ride TT bikes, it’s perfect – stiff, fast, aero and responsive. For the weekend triathlete, even for Ironman competitors, it’s a good mix, and you don’t need a training bike and a race bike. This one does it all.”
The Road Test
When you look at the Propel, then ride it, there are not a whole lot of surprises. It looks fast, mean and stiff, and it’s all those things. Despite its narrower tube shapes it really is stiff: thin seat stays that attach low on the seat tube mean the rear triangle is very compact, giving the back end a stiffness and feeling of solidarity in every direction.
The front end is much the same – the steering is precise, the ride is stiff and not entirely comfortable, and the overall feel is one of responsive agility.
The integrated seatpost means that the ride is always going to be a little rough, but that’s what you get when you buy a bike like this. It’s never going to be labelled ‘comfortable’, but neither is it unbearable.
What really seems to make this bike a winner is its versatility – ironic, when the Giant design and engineering honchos insist on their unwillingness to compromise. Putting comfort to one side, the Propel has it all: it’s fast, stiff, light, you can corner on it, time trial on it, climb on it and sprint on it too.
The chart above shows results of Giants in house tests of the Propel Advanced SL compared against competitor’s aerodynamic road bikes, up to a yaw angle of 15 degrees. They’ve tested each bike with the same Giant P-SLR1 wheels, Shimano Dura-Ace 7900 groupsets and standard bars, stems and Fizik Arione saddle.
In the past Giant have appeared to focus on the results of the tests conducted on their own products, but have rarely mentioned the competition. They seem to have changed their tune with the Propel, however, confidently claiming several key competitors are not only less aerodynamic but heavier, too. According to Giant, the new Propel is 36 seconds faster in a 40km time trial (at 40km/h) and 458g lighter than a comparable Ridley Noah FAST, 32 seconds faster and 324g lighter than a Specialized S-Works Venge, 36 seconds faster and 233g lighter than a Scott Foil Team Issue, and even 12 seconds faster – and a massive 546g lighter – than Cervélo’s S5 Team.
Giant fitted the Propel with its own aero integrated cockpit, while the other bikes were equipped with their usual front end. According to Swanson, the aero cockpit only makes a slight difference at yaw angles between zero and five degrees, though, and didn’t affect the test overall. Likewise, while the data presented was done with Giant’s own PSL1 wheelset, Swanson says they did test the bikes with wide-format wheels and the resultant order was unchanged.
All of the testing was done with a single, round water bottle mounted to the down tube – a much more realistic configuration than with no bottles mounted, which is what is usually done.
While improving aerodynamics was the priority for the new Propel, Giant says enormous efforts were made to ensure other performance metrics weren’t overlooked. Of the bikes Giant tested, they claim other notable results; front end stiffness second only to the Foil, pedaling stiffness falls closely behind the Noah FAST and the Venge, and ride quality is a close cousin to the company’s venerable TCR Advanced SL.
“It had to be the fastest bike in the world but it also had to be lighter than every other bike in the world and as stiff as the TCR Advanced SL,” Swanson said. “We knew that last one would be pretty much impossible but those were our goals.”
“It’s not the stiffest bike in the world but I’m okay with that,” he continued. “At the top end of this, we’re all really close. We’re so close that in the real world it’s virtually impossible to pick out a difference between the top three.”
If the new Propel Advanced SL supposedly offers similar stiffness, ride quality, and weight characteristics to the current TCR Advanced SL flagship as Giant claims, it begs the question of where that model stands in relation to the new aero bike – and if it’s even still relevant.
Apparently ‘similar’ and ‘equal’ are not the same, and Swanson says the TCR Advanced SL still outperforms the Propel in terms of non-aero performance – but not by much. Riders who prioritise stiffness, ride quality and light weight will probably still want to go with the more structurally efficient TCR.
Geometry is wholly carried over from the TCR Advanced SL, too. The overall verdict? It’s a winner.
Giant will offer two Propel Advanced SL models in March; the $7,990.00 Propel Advanced SL 0 with Shimano Dura-Ace Di2 9070 and Giant’s new Contact SLR Aero Integrated one-piece bar and stem, and the $6,199 Propel Advanced SL 1 with Dura-Ace 9000 and separate Giant Contact SLR Aero carbon handlebar and stem.
Both Propel Advanced SL machines will include Giant’s P-SLR1 Aero clincher wheels and the same SpeedControl SLR brakes.
Envie for Women
Accompanying the new Giant Propel Advanced SL is the women’s-specific Liv/Giant Envie Advanced, which features the same aerodynamic performance but specific geometry (a shorter top tube and taller head tube are the key differences to the frame), along with a slightly softer bottom bracket, Advanced-grade composite material, and a telescoping seatpost. Claimed frame weight climbs to 970g for a size small.
Liv/giant’s product developer Abby Santurbane explains that the Envie was designed using the company’s so-called ‘3F’ philosophy: Fit (geometry, sizes, components), Form (“we want the woman to walk into a bike shop and fall in love with the product”), and Function (technology, innovation and ride quality). Notably, all of the company people involved in Liv/giant bikes are women, including the marketing staff, engineers and industrial designers.
Multiple World Champion Marianne Vos, who was instrumental in the research and development for the Envie line, is understandably a big fan. “I was looking for a bike that gives me an aero advantage, but still allows me to break away, sprint and climb. The Envie Advanced is that bike.”
Liv/giant will offer two different Envie Advanced options; the $3,599 Envie Advanced 1, with Shimano Ultegra 6700 (compact chainrings), separate Giant Contact SLR Aero handlebar and stem, aluminium Giant SpeedControl SL brakes and Giant P-SL0 wheels, and the $2,799 Envie Advanced 2, with Shimano 105 (compact chainrings), Giant Connect SL handlebar, Giant SpeedControl brakes, and Giant P-SL1 wheels.
Five sizes are available, with effective top tube lengths ranging from 50cm to 56.5cm, and should be suitable for to fit female riders from under 1.5m/5ft to over 1.8m/6ft tall.