7 AERODYNAMIC OPTIMIZATION FACTORS
In cycling, different forces oppose the progress of the cyclist and his bicycle, thus limiting his speed of movement. At high speeds (over 40 km / h), aerodynamic drag is the most important of all these forces.
To understand its importance, you should know that 90% of the power produced by a cyclist is used to overcome this resistance. Aerodynamics is a major issue for cycling research, the main objective being to improve performance. Let's take a look at seven routes used by the best athletes and which can be used by trackers of all levels.
1. The geometry and characteristics of the bike
Unlike its on-road counterpart, a trail bike has a fixed sprocket and no brake, which means riders stop by decreasing their pedaling pace. The crank axle is higher to prevent the pedals from hitting the track in bends, where the slope is particularly steep. A tighter angle between the seat post and the top tube promotes power. Sprinters use handlebars with a traditional handlebar while time trial specialists use extenders to adopt a more aerodynamic stance. An aero frame also allows a much better penetration into the air than round tubes.
The manufacturers of track bikes are required to respect the rules decreed by the UCI which ensure - while allowing the pursuit of technological development - a fair and balanced competition based primarily on human performance and not on the benefits provided by machine itself.
2. The choice of wheels
The use of the solid wheel is required. Authorized at the front and at the rear during time trials, they offer better aerodynamics, but are heavier and less manoeuvrable. Many riders also choose a front wheel with three, four or five spokes, offering a good compromise to cut through the air while remaining light and responsive.
3. The second skin
The suit is the most aerodynamic outfit the racer can wear. State-of-the-art suits use the most advanced materials and technologies to reduce drag force. Fabrics and seams are strategically placed, often after wind tunnel testing. It is estimated that 80% of the drag created by the bike-rider combination comes from the rider, which underlines the importance of a suit that hugs the body.
A rider can save up to 30 watts (or more) if they find the right balance between aerodynamics and comfort.
The UCI Regulations guarantee that the suits do not alter the morphology (silhouette) of the cyclist and prohibit any non-essential accessory for purposes other than protection. Changes in the surface of the garment must be made by stitching the fabrics together, by weaving or sewing, and the grain of the fabric (surface roughness) cannot exceed 1 mm.
4. Aero helmets
Aero helmets have been used for many years to improve air penetration over their ventilated counterparts, which are great for tackling long distances on the road, but which will disrupt the air and create trails. Most track cyclists use helmets with a spike on the back. It also helps control currents as long as the runner follows their head horizontally to maintain continuity between the head and back.
Many also use visors, to boost aerodynamic gains, which can reach 25 watts.
5. Socks and shoe covers
Aero socks and shoe covers are ubiquitous at the highest level because they save a few watts.
Riders must however remain within the framework of the UCI regulations, which stipulate that these accessories must not exceed the middle of the calf.
6. Chain reaction
Specially designed or lubricated chains are very popular today in the UCI World Cup. Bradley Wiggins did a lot for their popularity when used to beat the UCI Hourly Record in 2015. His had been treated with a special lubricant which was said to save 5 watts. Such a product is now accessible to the general public.
The ultrasonic bath chain: the proposed waves of bubbles that will first clean the chain before penetrating the lubricant deeply to reduce friction between the links and improve transmission ... which promotes speed!
7. Measure the aerodynamics
To go fast, you have to overcome the resistance of the air first and foremost. The cyclist / bicycle pair must be as homogeneous as possible. Position takes on all its importance when you know that to double your speed you have to develop 8 times more power.
The postural study provides the most aerodynamic position. Combined with a biomechanical optimization study, it provides the best balance.
Cyclists continue to pursue even the smallest advantage. They resort to aero gloves, huge chains and even end caps for their extenders to have over their rivals. All this is part of the union between athlete, machine and engineering for fast and exciting lessons.
Source: Union cycliste internationale | Uci.ch and WattLab
(Mouse Over the image to see the animation)
Position "Tuck" surbaissée
Roue à disque av.
Guidon TT optimisé
Gain en seconde sur 4 km
Roue à disque arr.