FULL SUSPENSION GRAVEL - NEW Specialized Diverge STR
There are plenty of figures about the new Scott Foil RC: it is 20% faster, 9% lighter and 10% more comfortable than its predecessor. We also received sufficient details about the entire design process. But the most important thing was the test rides. Fortunately, those were more than worth it.
The objectives for this Foil were clear: better aerodynamics, more comfort and lower weight. The geometry is the same as that of the Addict RC. To determine that geometry, one first looks for the contact points, after which the chainstay length, head tube angle, fork offset, bottom bracket height and others can be determined. Of course, the straight seat tube stands out, but if you assume an average saddle height per size, the position has remained the same compared to the previous Foil.
The designers first determine the side view and then fill in the details. After the changes in the UCI regulations, tubes can be made a bit bigger, but if you don't want a very heavy bike, don't overdo it. To estimate the weight, one simply calculates the area.
Smooth transitions are also important for performance and ideal form should be extended as far as possible. That is why a first 3D model is created, which is adjusted, after which those adjustments are reviewed between the departments of the designers and engineers. And whether you ride size 49 or size 61, you always start from a new sketch. Scott did not design the Foil as a frameset but as a system, so the frame is also reconsidered when adjusting the handlebars.
The aero theme is continued in the graphic design, as you can see from the stripes on the down tube with the logo.
The narrower fork tube allows room for the cables around it, so they can pass without friction. The Di2 battery holder is housed in the bottom bracket compartment. You can replace the front derailleur holder with a plate if you want to ride with a single front ring.
The trade-off between comfort and efficiency turned out to be simple. The whole bike is focused on maximum power transfer, while the seatpost is the only real comfort zone. Stiffness vs. weight is another such compromise. To optimize that, the frame is made of four parts, with five connections. Finite Element Analysis (FEA) was then used to digitally examine how the carbon mats had to be arranged. That resulted in 558 different parts for the SL version. The software makes it possible to visualize where the most stress occurs in the frame. To strengthen a certain part, one looks at how much heavier the frame becomes and how much stiffness it provides. With a simple mathematical formula one knows whether it is worth doing or not.
A bare frame of the Foil weighs 805 grams. If you add paint, the battery case, clamps, rivets and dropouts, you get a total of just 915 grams for the SL and 985 grams for the slightly less sophisticated regular version. As a result, the Foil 3 is more than 100 grams lighter than the Foil 2. The bottom bracket stiffness is set at 60 N/mm and the headset stiffness at 92 N/mm, which corresponds to the figures that the Addict RC can present. That was the goal, because Team DSM is happy with that bike.
The third generation of the Foil has been worked on for no less than three years. The first half of that went entirely to the general design and aerodynamics developments. In doing so, a decision is first made on the tube profile, but in the end the complete picture of bicycle with rider is examined, in order to have a bicycle that is efficient in real conditions. CFD (Computational Fluid Dynamics) analysis is used at each step, after which the results are validated in the wind tunnel.
The designers start with the NACA profile, the shape used to make wings. From that NACA profile, the tail is cut off. Where and how that happens is a trade-off in terms of weight, aerodynamics and stiffness. Asymmetrical profiles are also used, for example at the front fork.
Aero expert Simon Smart: “We used to only have the wind tunnel, but then we learned to work with CFD software. This allowed us to reduce the guesswork. A fast bicycle also has to take into account the cyclist himself, because he is responsible for three quarters of the air resistance, while a bicycle only 20% and wheels barely 5%. In the wind tunnel you can repeat tests well and reliably, but it becomes more and more difficult due to the smaller profits that can still be achieved. In addition, the bicycle industry has different requirements than aircraft or car manufacturing. The speeds are lower and there are many influences. One of those influences is the 'yaw angle', the angle that is determined by the wind in combination with the self-developed speed. Usually that yaw angle is between 4 and 10 degrees.
During the first week in the wind tunnel, a lot of work is done with clay to make adjustments to the prototype and to check their influence. For example, we have seen that it does not pay to make a hollow in the oblique tube for the water bottle. The second prototype is already much cleaner.
The new Foil does have some peculiarities. For example, the flattened tubes of the seatstays are turned ten degrees inwards, an operation that offers 0.64 watts of gain because the airflow runs through the rotating spokes. A thin fork crown did 0.6 watts better than the thicker ones. The steering wheel is also an important part of the design. In total, the new Foil is 1 minute 18 seconds faster over 40 kilometers compared to the previous one. This measurement is representative of a professional rider in a solo flight at 40 km/h in average conditions, so with a mix of different yaw angles. The makers could also indicate that there are no major differences between the gain in low versus high speeds. So the curve is very stable.
The bike is made for rims from 40 to 60 mm high and comes with a narrower and therefore more aerodynamic front tire of 25 mm and a more comfortable rear tire of 28 mm, around which the bend of the seat tube is also made.
With an aero racing bike, it is mainly the tires that should provide comfort. That is why the Foil offers space for tires with a width of 30 millimeters. The steeper and taller seat tube, inevitably reminiscent of the Cervélo S5 with its curvature around the rear wheel, provides aerodynamic advantage but automatically creates a harder seatpost. That's why that pin is made in two parts, with a narrow front part that can bend around the hollowed-out back part. There is 109 millimeters left to bend. At the same time, you do not get too much movement from front to back, which is otherwise often experienced as annoying. To keep things reliable, Scott uses a special silicone grease between the two parts, and you should check the proper functioning every 1000 kilometers.
A nice detail is the option to mount a rear light, which is available as an extra. If you don't use the Campbell 20 Aero iL Rear Light, replace it with a lighter cover. As usual, sister brand Syncros provides these kinds of accessories. The rechargeable light weighs only 40 grams and offers a light output of 20 lumens. The rear light only fits the Duncan SL Aero Comfort seatpost of 270 grams, but a full seat post is also available that is lighter at 190 grams, and available in two lengths, with an offset of 0 or 15 mm. The seatposts have a head that is compatible with round and oval, carbon saddle rails.
The cockpit weighs just 335 grams (in size 420/110) and is even more aero than the Addict RC. It is available in widths from 380 to 440 mm and virtual stem lengths from 70 to 140 mm. The compact bend invites you to sit deeply. In addition, there is a separate combo with a 200 gram stem and a carbon or aluminum handlebar (255 or 360 grams) with a similar aero shape to the one-piece cockpit. The cables are hidden under the stem.
Prices have not yet been announced. Scott says that will depend on the exchange rate and circumstances of when the bikes become available, which should be by the end of 2022. There will be five versions of the Scott Foil RC, with the Ultimate as the banner. It is the only one to show off the HMX SL frame, alongside SRAM Red eTap AXS with power meter, Zipp 454 NSW wheels and Creston iC SL Aero cockpit. The Pro (Dura-Ace Di2, Dura-Ace C50), 10 (Ultegra Di2, Syncros Capital carbon wheels), 20 (SRAM Rival eTap AXS, Syncros carbon) and 30 (to be confirmed) complete the range.
To get a solid first impression, we were allowed to take three varied rides with the second model in the line, the Foil RC Pro, which is very similar to the model that Team DSM will ride from the Tour de France. We looked for a number of climbs and descents, interspersed with some flatter passages, to check out the versatile nature of the Foil RC. A group ride was ideal to check the steering qualities, while a passage on a race track gave us insight into the fast character of the bike.
We often thought back to our test with the light Addict RC. It turned out to be very quick and direct. With the Foil RC, the steering precision came back very clearly. It steers perfectly to the point where you want it. In acceleration, both uphill and on the flat, he could hide less that he is an aero bike, because there always seemed to be a little delay on that gear. After that first push, it seems to have enough stiffness to get you going, but it excels most at maintaining the speed. In short, it handles razor-sharp, but it's not the fastest bike of all.
The comfort is obviously not at the level of an endurance road bike, but thanks to the supple Vittoria Corsa Control TLR tires we didn't feel broken when we got back off the bike. If you want a softer ride, you just have to use the full 30 mm tire space, but we suspect that potential buyers mainly opt for the speed gain that you can achieve with this Scott. The aero qualities cannot of course be scientifically proven during a simple test drive, but it was noticeable that we were on the road faster than the previous days. This positions the Foil RC in the middle between more straight-on speed and comfort-oriented aero racers such as the BMC Timemachine Road or Ridley Noah Fast, and the nervous, hyper-direct speed monsters among aero bikes, like the now-disappeared Specialized Venge. In addition, the low weight speaks in favor of the Foil RC, because riders don't have to trade it in for the Addict RC if it's a bit uphill. Those who often find themselves in a solo escape will undoubtedly feel attracted to it.
For more information or to place a pre-order please call a member of our sales team on 01892 527069.
Ref. Steven Kins, Scott/Markus Greber; Grinta.be magazine. (26.06.2022).
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