Giant Propel Advanced SL3: Inside tech
Giant Propel and Envie launch
When the biggest bike manufacturer in the world invites you to see a new line of bikes, you take notice. So when Giant gave us the UK exclusive story on its new aerodynamic road bike, we were all over it like the proverbial bad suit.
When it comes to aero bike designs, there are three conflicting requirements for the frame: stiffness, aerodynamics and low mass. In the past, you've basically had to pick two and compromise, sometimes heavily, on the third. Giant says it has managed to hit all three with the new Propel and Envie bikes. Being the cynical types we are, we were keen to see some proof.
When you consider the resources at the disposal of the world's biggest bike manufacturer, and consider that the aero road bike is a new venture for the brand, it's hardly a surprise that they went back to basics, to square-one, before they set out to design the new frame.
If you look at the engineering papers published by other bike manufacturers on their bikes and testing procedures, it's clear that there are various types of tests undertaken in the development of a new bike. Each manufacturer has a different test protocol.
Sometime these differences are born out of limited resources, time or money, but most often out of the difficulties of the wind-tunnel testing. And this is what makes the Giant Propel stand out from the rest.
Long and windy road
Starting with a fresh sheet of paper meant Giant was able to create a test that better simulated the real world.
It wouldn't merely have wheels spinning on a rolling road inside the wind tunnel with a static mannequin sitting on top of the bike. Instead, it used a three-dimensional model of a real rider, legs spinning with the pedals to simulate riding - this last part of the protocol makes the Giant test more realistic.
To do this, Giant used a retired rider formerly of the Rabobank team, Grischa Niermann. They got him scanned into a computer so that the same model could be used for the computer-based CFD tests but also made him into a mannequin which they imaginatively called Niermann2. This way, the wind tunnel tests would use the same rider and in so doing validate the CFD work.
Team liaison mechanic Andy Wollyn explained how using Niermann2 was a major challenge - getting the ankles, knees and hips to articulate in a manner that replicated a real rider took literally months of work. To get the legs to ‘ride' was fairly easy once the limbs moved properly, yet it took an imaginative mind.
A special ‘non-freehub' body was built for the wheels so that the rolling road floor, which turned the wheels, would send the force back up the drivetrain into the pedals and thus turn the artificial legs of Niermann2.
Why go to all this effort? Why not just use a real person rather than a mannequin? Well, the big problem with using a person in the wind tunnel is the repeatability of tests. As a rider gets tired, their position changes and the results alter, meaning that, as you try different set-ups, you can't be sure what caused the change, bike or rider.
Niermann2 allows the designer and engineers to test against a ‘real' rider that is pedalling, and then compare directly against the competition - rather than trying to speculate on the effect of the wind hitting turning legs.
Another key factor in the test was that Giant chose to test the bikes at a lower wind speed than that at which most manufacturers choose to test. Rather than test at a 50kph, which is unsustainable for the average rider, Giant went with a more realistic 40kph.
This lower speed was deemed more relevant to the average consumer, whereas sustaining 50kph is achievable only by WorldTour riders. In the same vein, Giant had the good sense to do all the testing with a regular bottle attached to the down tube, rather than none.
With an accurate and repeatable test now possible - including a ‘pedalling rider' - the next step was to narrow down the frame design with a number of aero features, some of which bear more than a passing resemblance to a time trial Trinity bike.
The stem looks very similar to the one found on the Trinity, and has been incorporated into an aerodynamic bar/stem combo. While the brakes also look very similar to those of the TT bike, they are a completely different version, designed to work with the new pull ratio that SRAM Red and Shimano 9000 Dura-Ace have adopted.
They look and work very similarly to mountain bike V-brakes and have pretty good stopping power to boot. The brakes are made by TRP specifically for this range and come in either alloy on the cheaper machines or carbon at the top end.
The reason the new bike took so long was in large part related to Giant's having set a no-compromise goal. Jon Swanson, Giant Global on-road manager, explained that he had gone into a meeting at the start of the project with his boss and said that the bike needed to be the best in all three performance areas. Things got quite heated but Swanson would not back down.
In the end, Giant's data shows that it has created a set of tube shapes that bettered the rest in aerodynamics and in weight while managing to also be one of the best in terms of stiffness, measured as a twisting force from front to rear of the bike. Giant states that it went through 88 revisions before getting to the final version - for comparison, typically a standard new model of bike might go through three to five revisions before being ready for the market.
Giant UK will have an advanced fleet of just 100 Propel Advanced SL3 bikes - it's ostensibly a 2014 model - available from dealers from April/May, priced at £4,499. These will be Ultegra-equipped and will offer Giant a chance to gauge customer opinions ahead of the launch of the full range - details on which are limited but sources tell us that they'll be available in the autumn and will all be 11-speed.
Giant Envie women's model
Launched at the same time as the men's road frame was the women's version, the Envie. Using the exact same tube profiles as the Propel, the Envie is the world's first women's-specific aero road bike and as such shows the commitment Giant has to developing the women's market.
The Envie line uses the next frame down from the Propel we saw at the launch the Advanced line; this means it uses a slightly lower level of carbon, drops the ISP (integrated seatpost) and will cost less, but otherwise still has all the key features that make the Propel so sleek.
Like the Propel, the Envie will be available in late spring with an early drop of just 40 bikes, featuring Shimano 105 and named Advanced 2 and will cost £2,199.
More info: www.giant-bicycles.com